I have a canvas with a background set to be lineargradientbrush....how do I then extract the color from this background at a particular mouse point (x,y)?
I can do this with a BitmappedImage fine...as this deals with pixels, not sure about a canvas though...
Thanks greatly in advance,
U.
The code posted by Ray Burns didn't work for me but it did lead me down the right path. After some research and experimentation I located the problems to be the bitmap.Render(...) implementation and the Viewbox it uses.
Note: I'm using .Net 3.5 and WPF so maybe his code works in other versions of .Net.
The comments were left here intentionally to help explain the code.
As you can see the Viewbox needs to be normalized with respect to the source Visual Height and Width.
The DrawingVisual needs to be drawn using the DrawingContext before it can be rendered.
In the RenderTargetBitmap method I tried both PixelFormats.Default and PixelFormats.Pbgra32. My testing results were the same with both of them.
Here is the code.
public static Color GetPixelColor(Visual visual, Point pt)
{
Point ptDpi = getScreenDPI(visual);
Size srcSize = VisualTreeHelper.GetDescendantBounds(visual).Size;
//Viewbox uses values between 0 & 1 so normalize the Rect with respect to the visual's Height & Width
Rect percentSrcRec = new Rect(pt.X / srcSize.Width, pt.Y / srcSize.Height,
1 / srcSize.Width, 1 / srcSize.Height);
//var bmpOut = new RenderTargetBitmap(1, 1, 96d, 96d, PixelFormats.Pbgra32); //assumes 96 dpi
var bmpOut = new RenderTargetBitmap((int)(ptDpi.X / 96d),
(int)(ptDpi.Y / 96d),
ptDpi.X, ptDpi.Y, PixelFormats.Default); //generalized for monitors with different dpi
DrawingVisual dv = new DrawingVisual();
using (DrawingContext dc = dv.RenderOpen())
{
dc.DrawRectangle(new VisualBrush { Visual = visual, Viewbox = percentSrcRec },
null, //no Pen
new Rect(0, 0, 1d, 1d) );
}
bmpOut.Render(dv);
var bytes = new byte[4];
int iStride = 4; // = 4 * bmpOut.Width (for 32 bit graphics with 4 bytes per pixel -- 4 * 8 bits per byte = 32)
bmpOut.CopyPixels(bytes, iStride, 0);
return Color.FromArgb(bytes[0], bytes[1], bytes[2], bytes[3]);
}
If you are interested in the getScreenDPI() function the code is:
public static Point getScreenDPI(Visual v)
{
//System.Windows.SystemParameters
PresentationSource source = PresentationSource.FromVisual( v );
Point ptDpi;
if (source != null)
{
ptDpi = new Point( 96.0 * source.CompositionTarget.TransformToDevice.M11,
96.0 * source.CompositionTarget.TransformToDevice.M22 );
}
else
ptDpi = new Point(96d, 96d); //default value.
return ptDpi;
}
And the usage is similar to Ray's. I show it here for a MouseDown on a canvas.
private void cvsTest_MouseDown(object sender, MouseButtonEventArgs e)
{
Point ptClicked = e.GetPosition(cvsTest);
if (e.LeftButton.Equals(MouseButtonState.Pressed))
{
Color pxlColor = ImagingTools.GetPixelColor(cvsTest, ptClicked);
MessageBox.Show("Color String = " + pxlColor.ToString());
}
}
FYI, ImagingTools is the class where I keep static methods related to imaging.
WPF is vector based so it doesn't really have any concept of a "pixel" except within a bitmap data structure. However you can determine the average color of a rectangular area, including a 1x1 rectangular area (which generally comes out as a single pixel on the physical screen).
Here's how to do this:
public Color GetPixelColor(Visual visual, int x, int y)
{
return GetAverageColor(visual, new Rect(x,y,1,1));
}
public Color GetAverageColor(Visual visual, Rect area)
{
var bitmap = new RenderTargetBitmap(1,1,96,96,PixelFormats.Pbgra32);
bitmap.Render(
new Rectangle
{
Width = 1, Height = 1,
Fill = new VisualBrush { Visual = visual, Viewbox = area }
});
var bytes = new byte[4];
bitmap.CopyPixels(bytes, 1, 0);
return Color.FromArgb(bytes[0], bytes[1], bytes[2], bytes[3]);
}
Here is how you would use it:
Color pixelColor = GetPixelColor(canvas, x, y);
The way this code works is:
It fills a 1x1 Rectangle using a VisualBrush that shows the selected area of the canvas
It renders this Rectangle on to a 1-pixel bitmap
It gets the pixel color from the rendered bitmap
On Microsoft Support, there is this article about finding the color of the pixel at the mouse cursor:
http://support.microsoft.com/kb/892462
Related
I have a task to create an image that will be printed. On the picture, I need to put a single uppercase letter (Upper case, [A-Z]).
The printed image size can vary between 15cm height, and 30cm height (including any size in between).
The letter needs to span the full height of the printed image.
When setting the font size, I see you can get the size of the text.
using (Image<Rgba32> img = new Image<Rgba32>(imageWidth, imageHeight))
{
img.Mutate(x => x.Fill(Rgba32.White));
img.MetaData.HorizontalResolution = 96;
img.MetaData.VerticalResolution = 96;
var fo = SystemFonts.Find("Arial");
var font = new Font(fo, 1350, FontStyle.Regular);
I can get the size of my text here:
SizeF size = TextMeasurer.Measure(group.Text, new RendererOptions(font));
However, as you can see, I hard coded the size for my font here. The height needs to be matched to the height of the image.
Is there any way to specify this, without stretching and losing quality? Is there a way I can specify the height, in pixels? Maybe there's coloration to the font size that I can use safely?
When I set the Font size to the pixel height of my Image, I am seeing this:
I'm not sure why the circled parts have gaps. I am setting my top left position of the left hand text, to 0,0.... and the top right hand point of the 'QWW' group to the width of the image, and 0 as Y. But I'd expect them to be flush against the size, and the bottom.
TextMeasurer is designed for measurer text in the context of line and words not on individual characters because it doesn't look at individual glyph forms instead looks at the font as a whole to measure against line spacing etc.
Instead you will want to render the glyph directly to a vector using the nuget package SixLabors.Shapes.Text. This will allow you to accurately measure the final glyph + apply scaling and transforms to guarantee the glyph lines up with the edges of your image. It also saves you having to perform any expensive pixel level operations except the final drawing of the glyph to the image.
/// <param name="text">one or more characters to scale to fill as much of the target image size as required.</param>
/// <param name="targetSize">the size in pixels to generate the image</param>
/// <param name="outputFileName">path/filename where to save the image to</param>
private static void GenerateImage(string text, Primitives.Size targetSize, string outputFileName)
{
FontFamily fam = SystemFonts.Find("Arial");
Font font = new Font(fam, 100); // size doesn't matter too much as we will be scaling shortly anyway
RendererOptions style = new RendererOptions(font, 72); // again dpi doesn't overlay matter as this code genreates a vector
// this is the important line, where we render the glyphs to a vector instead of directly to the image
// this allows further vector manipulation (scaling, translating) etc without the expensive pixel operations.
IPathCollection glyphs = SixLabors.Shapes.TextBuilder.GenerateGlyphs(text, style);
var widthScale = (targetSize.Width / glyphs.Bounds.Width);
var heightScale = (targetSize.Height / glyphs.Bounds.Height);
var minScale = Math.Min(widthScale, heightScale);
// scale so that it will fit exactly in image shape once rendered
glyphs = glyphs.Scale(minScale);
// move the vectorised glyph so that it touchs top and left edges
// could be tweeked to center horizontaly & vertically here
glyphs = glyphs.Translate(-glyphs.Bounds.Location);
using (Image<Rgba32> img = new Image<Rgba32>(targetSize.Width, targetSize.Height))
{
img.Mutate(i => i.Fill(new GraphicsOptions(true), Rgba32.Black, glyphs));
img.Save(outputFileName);
}
}
I split up your question into 3 parts:
dynamic font size, rather than hard coded font size
the glyph should use the full height of the image
the glyph should be aligned to the left
Dynamically scale the text to fill the height of the image
After measuring the text size, calculate the factor by which the font needs to be scaled up or down to match the height of the image:
SizeF size = TextMeasurer.Measure(text, new RendererOptions(font));
float scalingFactor = finalImage.Height / size.Height;
var scaledFont = new Font(font, scalingFactor * font.Size);
This way the initially set font size is largely ignored. Now we can draw the text with the dynamically scaled font, depending on the height of the image:
Inflate text to use the entire height of the image
Depending on each glyph, we might now have a gap in between the top/bottom side of the image and the top/bottom side of the text. How a glyph is rendered or drawn depends heavily on the font in use. I am not an expert in typography, but AFAIK every font has it's own margin/padding, and has custom heights around the baseline.
In order for our glyph to align with the top and bottom of the image, we have to further scale up the font. To calculate this factor, we can determine the top and bottom edge of the currently drawn text by searching for the height (y) of the top-most and bottom-most pixels, and scale up the font with this difference. Additionally, we need to offset the glyph by the distance from the top of the image to the top edge of the glyph:
int top = GetTopPixel(initialImage, Rgba32.White);
int bottom = GetBottomPixel(initialImage, Rgba32.White);
int offset = top + (initialImage.Height - bottom);
SizeF inflatedSize = TextMeasurer.Measure(text, new RendererOptions(scaledFont));
float inflatingFactor = (inflatedSize.Height + offset) / inflatedSize.Height;
var inflatedFont = new Font(font, inflatingFactor * scaledFont.Size);
location.Offset(0.0f, -top);
Now we can draw the text with the top and the bottom snapping to the top and bottom edges of the image:
Move glyph to the very left
Lastly, depending on the glyph, the left side of the glyph might not snap with the left side of the image. Similar to the previous step, we can determine the left-most pixel of the text within the current image containing the inflated glyph, and move the text accordingly to the left to remove the gap in between:
int left = GetLeftPixel(intermediateImage, Rgba32.White);
location.Offset(-left, 0.0f);
Now we can draw the text aligning with the left side of the image:
This final image now has the font dynamically scaled depending on the size of the image, has been further scaled up and moved to fill up the entire height of the image, and has been further moved to have no gap to the left.
Note
When drawing the text, the DPI of the TextGraphicsOptions should match the DPI of the image:
var textGraphicOptions = new TextGraphicsOptions(true)
{
HorizontalAlignment = HorizontalAlignment.Left,
VerticalAlignment = VerticalAlignment.Top,
DpiX = (float)finalImage.MetaData.HorizontalResolution,
DpiY = (float)finalImage.MetaData.VerticalResolution
};
Code
private static void CreateImageFiles()
{
Directory.CreateDirectory("output");
string text = "J";
Rgba32 backgroundColor = Rgba32.White;
Rgba32 foregroundColor = Rgba32.Black;
int imageWidth = 256;
int imageHeight = 256;
using (var finalImage = new Image<Rgba32>(imageWidth, imageHeight))
{
finalImage.Mutate(context => context.Fill(backgroundColor));
finalImage.MetaData.HorizontalResolution = 96;
finalImage.MetaData.VerticalResolution = 96;
FontFamily fontFamily = SystemFonts.Find("Arial");
var font = new Font(fontFamily, 10, FontStyle.Regular);
var textGraphicOptions = new TextGraphicsOptions(true)
{
HorizontalAlignment = HorizontalAlignment.Left,
VerticalAlignment = VerticalAlignment.Top,
DpiX = (float)finalImage.MetaData.HorizontalResolution,
DpiY = (float)finalImage.MetaData.VerticalResolution
};
SizeF size = TextMeasurer.Measure(text, new RendererOptions(font));
float scalingFactor = finalImage.Height / size.Height;
var scaledFont = new Font(font, scalingFactor * font.Size);
PointF location = new PointF();
using (Image<Rgba32> initialImage = finalImage.Clone(context => context.DrawText(textGraphicOptions, text, scaledFont, foregroundColor, location)))
{
initialImage.Save("output/initial.png");
int top = GetTopPixel(initialImage, backgroundColor);
int bottom = GetBottomPixel(initialImage, backgroundColor);
int offset = top + (initialImage.Height - bottom);
SizeF inflatedSize = TextMeasurer.Measure(text, new RendererOptions(scaledFont));
float inflatingFactor = (inflatedSize.Height + offset) / inflatedSize.Height;
var inflatedFont = new Font(font, inflatingFactor * scaledFont.Size);
location.Offset(0.0f, -top);
using (Image<Rgba32> intermediateImage = finalImage.Clone(context => context.DrawText(textGraphicOptions, text, inflatedFont, foregroundColor, location)))
{
intermediateImage.Save("output/intermediate.png");
int left = GetLeftPixel(intermediateImage, backgroundColor);
location.Offset(-left, 0.0f);
finalImage.Mutate(context => context.DrawText(textGraphicOptions, text, inflatedFont, foregroundColor, location));
finalImage.Save("output/final.png");
}
}
}
}
private static int GetTopPixel(Image<Rgba32> image, Rgba32 backgroundColor)
{
for (int y = 0; y < image.Height; y++)
{
for (int x = 0; x < image.Width; x++)
{
Rgba32 pixel = image[x, y];
if (pixel != backgroundColor)
{
return y;
}
}
}
throw new InvalidOperationException("Top pixel not found.");
}
private static int GetBottomPixel(Image<Rgba32> image, Rgba32 backgroundColor)
{
for (int y = image.Height - 1; y >= 0; y--)
{
for (int x = image.Width - 1; x >= 0; x--)
{
Rgba32 pixel = image[x, y];
if (pixel != backgroundColor)
{
return y;
}
}
}
throw new InvalidOperationException("Bottom pixel not found.");
}
private static int GetLeftPixel(Image<Rgba32> image, Rgba32 backgroundColor)
{
for (int x = 0; x < image.Width; x++)
{
for (int y = 0; y < image.Height; y++)
{
Rgba32 pixel = image[x, y];
if (pixel != backgroundColor)
{
return x;
}
}
}
throw new InvalidOperationException("Left pixel not found.");
}
We don't need to save all 3 images, however we do need to create all 3 images and inflate and move the text step by step in order to fill up the entire height of the image and start at the very left of the image.
This solution works independently of the used font. Also, for a production application avoid finding a font via SystemFonts, because the font in question might not be available at the target machine. To have an stable stand-alone solution, deploy a TTF font with the application and install the font via FontCollection manually.
I am capturing InkStrokes and have a need to create a scaled bitmap image of the strokes in the background. The captured images need to be of uniform size regardless of how big the bounding box of the ink.
For example, if original ink stroke is drawn and the bounding box top/left is 100,100 and size is 200,200 on the ink canvas, I want the ink to start at 0,0 of the new rendered bitmap that is 50,50 size (ignore impact of stroke width right now).
I have figured out how to scale the ink strokes (thanks StackOverflow) but not how to move the strokes. Right now, it seems I have to create a bitmap the size of the InkCanvas, render the scaled ink, then crop bigger image to the correct size.
I've tried using the InkStroke.PointTranslate via
var scaleMatrix = Matrix3x2.CreateScale(scale);
scaleMatrix.Translation = -offset; // top/left of ink stroke bounding box
stroke.PointTransform = scaleMatrix;
But the coordinates do not come out correct.
Any help much appreciated.
You can combine transformations by multiplying matrices. This works for me
var strokes = inkCanvas.InkPresenter.StrokeContainer.GetStrokes();
var boundingBox = inkCanvas.InkPresenter.StrokeContainer.BoundingRect;
var matrix1 = Matrix3x2.CreateTranslation((float)-boundingBox.X, (float)-boundingBox.Y);
var matrix2 = Matrix3x2.CreateScale(0.5f);
var builder = new InkStrokeBuilder();
var newStrokeList = new List<InkStroke>();
foreach (var stroke in strokes)
{
newStrokeList.Add(builder.CreateStrokeFromInkPoints
(stroke.GetInkPoints(), matrix1 * matrix2));
}
//Add the translated and scaled strokes to the inkcanvas
inkCanvas.InkPresenter.StrokeContainer.AddStrokes(newStrokeList);
Maybe I was still doing something wrong, but it appears you cannot use InkStrokeBuilder.CreateStrokeFromInkPoints with more than one kind of transform. I tried all kinds of combinations/approaches, and just could not get it to work.
Here is my solution...
private static IList<InkStroke> GetScaledAndTransformedStrokes(IList<InkStroke> strokeList, float scale)
{
var builder = new InkStrokeBuilder();
var newStrokeList = new List<InkStroke>();
var boundingBox = strokeList.GetBoundingBox();
foreach (var singleStroke in strokeList)
{
var translateMatrix = new Matrix(1, 0, 0, 1, -boundingBox.X, -boundingBox.Y);
var newInkPoints = new List<InkPoint>();
var originalInkPoints = singleStroke.GetInkPoints();
foreach (var point in originalInkPoints)
{
var newPosition = translateMatrix.Transform(point.Position);
var newInkPoint = new InkPoint(newPosition, point.Pressure, point.TiltX, point.TiltY, point.Timestamp);
newInkPoints.Add(newInkPoint);
}
var newStroke = builder.CreateStrokeFromInkPoints(newInkPoints, new Matrix3x2(scale, 0, 0, scale, 0, 0));
newStrokeList.Add(newStroke);
}
return newStrokeList;
}
I ended up having to apply my own translate transform then use the builder.CreateStrokeFromInkPoints with a scale matrix applied to get the results I wanted. GetBoundingBox is my own extension:
public static class RectExtensions
{
public static Rect CombineWith(this Rect r, Rect rect)
{
var top = (r.Top < rect.Top) ? r.Top : rect.Top;
var left = (r.Left < rect.Left) ? r.Left : rect.Left;
var bottom = (r.Bottom < rect.Bottom) ? rect.Bottom : r.Bottom;
var right = (r.Right < rect.Right) ? rect.Right : r.Right;
var newRect = new Rect(new Point(left, top), new Point(right, bottom));
return newRect;
}
}
My program is sort of copy version of MS paint and Pickpick.
and one of features is rasterizing the selected object such as textblock or shape.
Regarding the selectable object, in order to resize and move with adorner,
it has 1 ContentControl which comprise 1 textblock + 1 shape.
ContentControl (able to resize, rotate, move)
└─> Textblock (bold, italic, V-align, H-align, word wrap...)
└─> Shape (can be a triangle, rectangle etc...)
It was not hard to convert to draw the shape with drawing context instead of render at Canvas.
var SH = CC.GetShape();
var TB = CC.GetTextBlock();
var visual = new DrawingVisual();
Geometry geo = null;
System.Windows.Media.Pen pen = null;
System.Windows.Media.Brush brush = null;
if (SH != null)
{
geo = SH.RenderedGeometry; // shape to geo
if (geo == null)
return;
pen = new System.Windows.Media.Pen(SH.Stroke, SH.StrokeThickness);
brush = SH.Fill;
}
using (var dc = visual.RenderOpen())
{
// Draw the background first
dc.DrawImage(first, new Rect(0, 0, first.Width, first.Height));
dc.PushTransform(new TranslateTransform(left, top));
// Draw the shape
if (SH != null && geo != null)
dc.DrawGeometry(brush, pen, geo);
}
But while drawing Textblock with drawing context,
I've referred below link to calculate the position of Textblock
Vertical alignment with DrawingContext.DrawText
but the problem is when the Textblock has multiline or word wrapped.
screenshot of my program
if (TB.Text.Equals(string.Empty) == false)
{
var typeface = new Typeface(CC.txtSetting.fontFamily,
CC.txtSetting.fontStyle,
CC.txtSetting.fontWeight,
FontStretches.Normal);
var formattedText = new FormattedText(TB.Text
, CultureInfo.CurrentCulture
, FlowDirection.LeftToRight
, typeface
, CC.txtSetting.fontSize
, new SolidColorBrush(CC.txtSetting.fontColor));
double centerX = CC.ActualWidth / 2;
double centerY = CC.ActualHeight / 2;
double txtPositionX = 0.0f;
double txtPositionY = 0.0f;
if (TB.TextAlignment == TextAlignment.Left)
{
txtPositionX = 1.0f;
}
else if (TB.TextAlignment == TextAlignment.Center)
{
txtPositionX = centerX - formattedText.WidthIncludingTrailingWhitespace / 2;
}
else if (TB.TextAlignment == TextAlignment.Right)
{
txtPositionX = CC.Width -
formattedText.WidthIncludingTrailingWhitespace - 1.0f;
}
if (TB.VerticalAlignment == VerticalAlignment.Top)
{
txtPositionY = 1.0f;
}
else if (TB.VerticalAlignment == VerticalAlignment.Center)
{
txtPositionY = centerY - formattedText.Height / 2;
}
else if (TB.VerticalAlignment == VerticalAlignment.Bottom)
{
txtPositionY = CC.Height - formattedText.Height - 1.0f;
}
var ptLocation = new System.Windows.Point(txtPositionX, txtPositionY);
dc.DrawText(formattedText, ptLocation);
}
Additionally, the textblock is wrapped by ContentControl so depending on user change the property of textblock, it will vary so much.
I guess it seems not possible to convert every variable.
So, I'm thinking alternative ways to draw.
Draw with GDI+ instead of drawing with drawing context. (still uncertain)
Use drawing context while the user is editing the text. (so it'll be the same before rasterizing and vice-versa)
Any way to directly convert/capture the Textblock into an image or Geometry? (it would be the best way if it's possible.)
For example, to get a shader effect applied image source, I did like this. so.. probably there's the way.
How can I get the object of effect-applied source
You can also refer to this program from http://ngwin.com/picpick
screenshot of picpick
Any better ideas? Thank you in advance.
I made it!
I could capture the particular control with RenderTargetBimap. Since ContentControl is a part of Visual Element.
CustomControl is inherited control from ContentControl.
public static BitmapSource ControlToBitmap(CustomControl control)
{
int W = (int)control.ActualWidth;
int H = (int)control.ActualHeight;
RenderTargetBitmap renderBitmap = new RenderTargetBitmap(
W, H,
96d, 96d, PixelFormats.Pbgra32);
// needed otherwise the image output is black
control.Measure(new System.Windows.Size(W, H));
control.Arrange(new Rect(new System.Windows.Size(W, H)));
renderBitmap.Render(control);
var BS = RenderTargetBitmapToBitmap(renderBitmap);
return BS;
}
Additionally, I had to deal with the angle. Because I couldn't capture the angled control directly. but my idea is
back up the angle value first.
And restore the control to be non-rotated(RotateTransform = 0.0)
Capture a non-rotated control to a bitmap.
Then rotate the captured bitmap again.
Combine both bitmaps into one.
public static void OverlayControl(ImageSource first, CustomControl CC)
{
if (CC == null)
return;
var visual = new DrawingVisual();
double left = Canvas.GetLeft(CC);
double top = Canvas.GetTop(CC);
// Get control's angle.
double rotationInDegrees = 0.0f;
RotateTransform rotation = CC.RenderTransform as RotateTransform;
if (rotation != null) // Make sure the transform is actually a RotateTransform
{
rotationInDegrees = rotation.Angle; // back up this to temp var.
rotation.Angle = 0.0f; // Set this to 0.0 to capture properly.
}
var second = ControlToBitmap(CC);
using (var dc = visual.RenderOpen())
{
// Draw the background image frist.
dc.DrawImage(first, new Rect(0, 0, first.Width, first.Height));
// Push angle if the control has rotated.
if (rotationInDegrees != 0.0f)
dc.PushTransform(new RotateTransform(rotationInDegrees, left + (CC.Width / 2), top + (CC.Height / 2)));
// transfrom as much as control moved from the origin.
dc.PushTransform(new TranslateTransform(left, top));
// Draw the second image. (captured image from the control)
dc.DrawImage(second, new Rect(0, 0, second.Width, second.Height));
// pop transforms
dc.Pop();
}
var rtb = new RenderTargetBitmap((int)first.Width, (int)first.Height,
96, 96, PixelFormats.Default);
rtb.Render(visual);
// Set as a one combined image.
MainWindow.VM.RenderedImage = rtb;
}
Now, everything seems alright.
I am currently working on a histogram renderer that renders bitmaps onto the Grasshopper canvas. There are a total of two bitmaps, both of them explained below
private readonly Bitmap _image;
and:
private readonly Bitmap _overlayedImage;
The Bitmap instance with the name _image looks like this:
_bitmap http://puu.sh/6mUk4/20b879710a.png
While the Bitmap instance with the name _overlayedImage looks like this:
Basically, _overlayedImage is a bitmap that is created using the _image bitmap, and as the name suggests, overlays the text (that you can see in the image I posted) and adds a black background to it. This is how it is assigned
_overlayedImage = overlayBitmap(_image, width * 3, height * 3, times, dates, colors);
(The * 3 is used to resize the image).
An issue I currently have is multi-fold.
Using this method, I am able to render _image onto the canvas.
The code is like this:
protected override void Render(Grasshopper.GUI.Canvas.GH_Canvas canvas, Graphics graphics, Grasshopper.GUI.Canvas.GH_CanvasChannel channel) {
// Render the default component.
base.Render(canvas, graphics, channel);
// Now render our bitmap if it exists.
if (channel == Grasshopper.GUI.Canvas.GH_CanvasChannel.Wires) {
var comp = Owner as KT_HeatmapComponent;
if (comp == null)
return;
List<HeatMap> maps = comp.CachedHeatmaps;
if (maps == null)
return;
if (maps.Count == 0)
return;
int x = Convert.ToInt32(Bounds.X + Bounds.Width / 2);
int y = Convert.ToInt32(Bounds.Bottom + 10);
for (int i = 0; i < maps.Count; i++) {
Bitmap image = maps[i].overlayedImage;
if (image == null)
continue;
Rectangle mapBounds = new Rectangle(x, y, maps[i].Width, maps[i].Height);
mapBounds.X -= mapBounds.Width / 2;
Rectangle edgeBounds = mapBounds;
GH_Capsule capsule = GH_Capsule.CreateCapsule(edgeBounds, GH_Palette.Normal);
capsule.Render(graphics, Selected, false, false);
capsule.Dispose();
graphics.DrawImage(image, mapBounds);
graphics.DrawRectangle(Pens.Black, mapBounds);
// some graphics interpolation and bicubic methods
y = edgeBounds.Bottom - (mapBounds.Height) - 4;
}
}
}
As per what comp.CachedHeatmaps; is:
private readonly List<HeatMap> _maps = new List<HeatMap>();
internal List<HeatMap> CachedHeatmaps {
get { return _maps; }
}
However, whenever I try to use Render() on the _overlayedImage, I am unable to do so.
I have isolated the issue to the Render() method, and it seems this line
Rectangle mapBounds = new Rectangle(x, y, maps[i].Width, maps[i].Height); is the main issue, as maps[i].Width and maps[i].Height returns 1 and 100 respectively, which are coincidentally the dimensions of the legend, which are 100 pixels vertically and 1 pixel horizontally.
I apologize for the decently long question, but I don't think I could have explained it any other way.
It turns out there are two issues:
In my main method I used _overlayedImage.Dispose(), which effectively destroyed the image before it was even displayed onto the canvas.
Also, my issue isolation was also correct. This line resulted in the thing rendering correctly:
Rectangle mapBounds = new Rectangle(x, y, maps[i].overlayedImage.Width, maps[i].overlayedImage.Height);
Resulting component:
I am doing sort of a limited graphics editor in a desktop application in c# 3.5 GDI. the user first selects an image which is shown in a picturebox control which is smaller in size so image resizing is done to fit the picture.
For cropping, the user selects the area to crop. there are a number of example on the net that explains how to crop the image but none of them explains the case when the area is selected on a thumbnail but the cropping is done on the original image i.e. some kind of mapping is done between the two images.
all the graphic editor provide similar functionality. can you direct me to a link which explains how to do this?
Sounds to me like you need to calculate the crop rectangle on the original image yourself based on the relative sizes of the picture and the thumbnail.
public static class CoordinateTransformationHelper
{
public static Point ThumbToOriginal(this Point point, Size thumb, Size source)
{
Point rc = new Point();
rc.X = (int)((double)point.X / thumb.Width * source.Width);
rc.Y = (int)((double)point.Y / thumb.Height * source.Height);
return rc;
}
public static Size ThumbToOriginal(this Size size, Size thumb, Size source)
{
Point pt = new Point(size);
Size rc = new Size(pt.ThumbToOriginal(thumb, source));
return rc;
}
public static Rectangle ThumbToOriginal(this Rectangle rect, Size thumb, Size source)
{
Rectangle rc = new Rectangle();
rc.Location = rect.Location.ThumbToOriginal(thumb, source);
rc.Size = rect.Size.ThumbToOriginal(thumb, source);
return rc;
}
}
Usage example:
Size thumb = new Size(10, 10);
Size source = new Size(100, 100);
Console.WriteLine(new Point(4, 4).ThumbToOriginal(thumb, source));
Console.WriteLine(new Rectangle(4, 4, 5, 5).ThumbToOriginal(thumb, source));
here's a really easy method to crop a System.Drawing.Image
public static Image CropImage(Image image, Rectangle area)
{
Image cropped = null;
using (Bitmap i = new Bitmap(image))
using (Bitmap c = i.Clone(area, i.PixelFormat))
cropped = (Image)c;
return cropped;
}
pass in an Image and the area that you want to crop and that should do it