I am drawing lines by using win32 gdi native apis. Now, I want to draw the line as transparent. I have set the alpha channel property in the color. However, setting the alpha channel in color is not drawing the line as transparent. I read about Alpha Blend Api but could not figure out the solution.
var hdc = g.GdiDeviceContext;
var srcHdc = CreateCompatibleDC(hdc);
var clipRegion = CreateRectRgn(x, y, x + width, y + height);
SelectClipRgn(hdc, clipRegion);
var pen = CreatePen(PenStyle.Solid, LineWidth, (uint)ColorTranslator.ToWin32(colour));
if (pen != IntPtr.Zero)
{
var oldPen = SelectObject(hdc, pen);
Polyline(hdc, points, points.Length);
SelectObject(hdc, oldPen);
DeleteObject(pen);
}
SelectClipRgn(hdc, IntPtr.Zero);
AlphaBlend(hdc, x, y, width, height, srcHdc, x, y, width, height, new BlendFunction(0x00, 0, 0x7f, 0x00));
DeleteObject(clipRegion);
I am trying to draw the line as transparent.
var srcHdc = CreateCompatibleDC(hdc);
This creates a memory device context. This is the right first step. But the memory dc is not ready yet. It requires a memory bitmap as well.
SelectObject(hdc, pen);
Polyline(hdc, points, points.Length);
This will draw on windows device context. But we want to draw on memory device context, and then draw the memory on to HDC using AlphaBlend
See example below:
int w = 100;
int h = 100;
//create memory device context
var memdc = CreateCompatibleDC(hdc);
//create bitmap
var hbitmap = CreateCompatibleBitmap(hdc, w, h);
//select bitmap in to memory device context
var holdbmp = SelectObject(memdc, hbitmap);
//begine drawing:
var hpen = CreatePen(0, 4, 255);
var holdpen = SelectObject(memdc, hpen);
Rectangle(memdc, 10, 10, 90, 90);
//draw memory device (memdc) context on to windows device context (hdc)
AlphaBlend(hdc, 0, 0, w, h, memdc, 0, 0, w, h, new BLENDFUNCTION(0, 0, 128, 0));
//clean up:
SelectObject(memdc, holdbmp);
SelectObject(memdc, holdpen);
DeleteObject(hbitmap);
DeleteObject(hpen);
DeleteDC(memdc);
Related
I am drawing multiple images over earh map, I am using perspective correct texturing link on each image.
I want to store rendered image in to file (sorce file is 1280x760, the rendered images is around 160x90 in most cases rotated). Currently I am doing this with GL.ReadPixels
int width = 1920;
int height = 1080;
using (Bitmap bitmap = new Bitmap(width, height))
{
System.Drawing.Imaging.BitmapData bits = bitmap.LockBits(new Rectangle(0, 0, width, height), System.Drawing.Imaging.ImageLockMode.WriteOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
GL.ReadPixels(0, (0, width, height, OpenTK.Graphics.OpenGL.PixelFormat.Bgra, PixelType.UnsignedByte, bits.Scan0);
bitmap.UnlockBits(bits);
bitmap.RotateFlip(RotateFlipType.Rotate180FlipX);
bitmap.Save("output.png", System.Drawing.Imaging.ImageFormat.Png);
}
The problem occurs when I move the map, rendered images are not visible anymore on the screen and it looks like that in this case GL.ReadPixels returns empty pixels.
How to get rendered image even if this is not currently rendered on screen?
Extra question, if I use framebuffer the result is the same but using the frame buffer I never see image on the screen, it looks like framebuffer is not drawn on the screen, but GL.ReadPixels can get image out.
Which lines of code are needed to draw framebuffer also on the screen?
Any idea?
I am adding some code with drawing in to framebuffer but the result is empty image.
int FBOHandle = 0;
int ColorTexture = 0;
int DepthTexture = 0;
public bool canRender = false;
public void onRender()
{
int zoom = (int)MainForm.mainMap.Zoom;
VideoMapOverlayBitmap pob = null;
lock (videoMapOverlayBitmapsSync)
videoMapOverlayBitmaps.TryGetValue(zoom, out pob);
if (pob == null)
return;
if (canRender)
{
canRender = false;
int fboWidth = 1920;
int fboHeight = 1080;
// Create Color Tex for framebuffer
GL.GenTextures(1, out ColorTexture);
GL.BindTexture(TextureTarget.Texture2D, ColorTexture);
GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba8, fboWidth, fboHeight, 0, OpenTK.Graphics.OpenGL.PixelFormat.Rgba, PixelType.UnsignedByte, IntPtr.Zero);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, (int)TextureWrapMode.ClampToBorder);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, (int)TextureWrapMode.ClampToBorder);
// GL.Ext.GenerateMipmap( GenerateMipmapTarget.Texture2D );
// Create Depth Tex for framebuffer
GL.GenTextures(1, out DepthTexture);
GL.BindTexture(TextureTarget.Texture2D, DepthTexture);
GL.TexImage2D(TextureTarget.Texture2D, 0, (PixelInternalFormat)All.DepthComponent32, fboWidth, fboHeight, 0, OpenTK.Graphics.OpenGL.PixelFormat.DepthComponent, PixelType.UnsignedInt, IntPtr.Zero);
// things go horribly wrong if DepthComponent's Bitcount does not match the main Framebuffer's Depth
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, (int)TextureWrapMode.ClampToBorder);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, (int)TextureWrapMode.ClampToBorder);
// GL.Ext.GenerateMipmap( GenerateMipmapTarget.Texture2D );
// Create a FBO and attach the textures
GL.Ext.GenFramebuffers(1, out FBOHandle);
GL.Ext.BindFramebuffer(FramebufferTarget.FramebufferExt, FBOHandle);
GL.Ext.FramebufferTexture2D(FramebufferTarget.FramebufferExt, FramebufferAttachment.ColorAttachment0Ext, TextureTarget.Texture2D, ColorTexture, 0);
GL.Ext.FramebufferTexture2D(FramebufferTarget.FramebufferExt, FramebufferAttachment.DepthAttachmentExt, TextureTarget.Texture2D, DepthTexture, 0);
//check for errors on framebuffer
FramebufferErrorCode errorCode = GL.Ext.CheckFramebufferStatus(FramebufferTarget.Framebuffer);
if (errorCode != FramebufferErrorCode.FramebufferComplete)
{
if (errorCode == FramebufferErrorCode.FramebufferUnsupported)
Console.WriteLine("FramebufferUnsupported");
OnUnload();
return;
}
GL.ClearColor(0, 0, 0, 0);
GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
/*
//this corrupts my main screen
GL.ClearColor(Color.White);
GL.MatrixMode(MatrixMode.Projection);
GL.LoadIdentity();
GL.Ortho(0, fboWidth, fboHeight, 0, -1, 1); // Up-left corner pixel has coordinate (0, 0)
GL.Viewport(0, 0, fboWidth, fboHeight); // Use all of the glControl painting area
*/
// Render all images
PureProjection proj = MainForm.mainMap.MapProvider.Projection;
List<VideoLogEntry> log = Log;
//go over all images in the loop
foreach (var videoEntry in log)
{
if (videoEntry == null)
continue;
if (videoEntry.projectedRectangleEmpty())
continue;
PointLatLng[] rect = videoEntry.getProjectedRectangle();
if (videoEntry.bmp != null)
videoEntry.createTexture();
GL.Enable(EnableCap.Texture2D);
GL.BindTexture(TextureTarget.Texture2D, videoEntry.texture);
//GL.Ext.FramebufferTexture2D(FramebufferTarget.FramebufferExt, FramebufferAttachment.ColorAttachment0Ext, TextureTarget.Texture2D, videoEntry.texture, 0);
//GL.DrawBuffers(1, new int[] { videoEntry.texture }); //compiler error
//Do the magick for "Perspective correct texturing"
// center point
GPoint localTargetPosition = MainForm.instance.gMapControl.FromLatLngToLocalWithOffset(videoEntry.target);
videoEntry.UpdatePolygonLocalPosition(videoEntry.projectedRectangle);
// determines distances to center for all vertexes
double dUL = Common.distance(new double[] { videoEntry.LocalPoints[0].X, videoEntry.LocalPoints[0].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
double dUR = Common.distance(new double[] { videoEntry.LocalPoints[1].X, videoEntry.LocalPoints[1].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
double dLR = Common.distance(new double[] { videoEntry.LocalPoints[2].X, videoEntry.LocalPoints[2].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
double dLL = Common.distance(new double[] { videoEntry.LocalPoints[3].X, videoEntry.LocalPoints[3].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
var texCoords = new[]
{
new Vector4(0, 0, 1, 1),
new Vector4(1, 0, 1, 1),
new Vector4(1, 1, 1, 1),
new Vector4(0, 1, 1, 1)
};
texCoords[0] *= (float)((dUL + dLR) / dLR);
texCoords[1] *= (float)((dUR + dLL) / dLL);
texCoords[2] *= (float)((dLR + dUL) / dUL);
texCoords[3] *= (float)((dLL + dUR) / dUR);
GL.Begin(PrimitiveType.Quads);
{
GL.TexCoord4(texCoords[0]); GL.Vertex4(videoEntry.LocalPoints[0].X, videoEntry.LocalPoints[0].Y, 1, 1); //UL LocalPoints[0] gimbalUL
GL.TexCoord4(texCoords[1]); GL.Vertex4(videoEntry.LocalPoints[1].X, videoEntry.LocalPoints[1].Y, 1, 1); //UR LocalPoints[1] gimbalUR
GL.TexCoord4(texCoords[2]); GL.Vertex4(videoEntry.LocalPoints[2].X, videoEntry.LocalPoints[2].Y, 1, 1); //LR LocalPoints[2] gimbalLR
GL.TexCoord4(texCoords[3]); GL.Vertex4(videoEntry.LocalPoints[3].X, videoEntry.LocalPoints[3].Y, 1, 1); //LL LocalPoints[3] gimbalLL
}
GL.End();
GL.Disable(EnableCap.Texture2D);
}
// Grab your screenshot
// draw FBO in to file
lock (pob.masterBitmapSync)
{
using (Bitmap mybitmap = new Bitmap(fboWidth, fboHeight))
{
//fill bitmal so we will see what ReadPixels draw
using (Graphics gfx = Graphics.FromImage(mybitmap))
using (SolidBrush brush = new SolidBrush(Color.FromArgb(0, 0, 255)))
{
gfx.FillRectangle(brush, 0, 0, mybitmap.Width, mybitmap.Height);
}
GPoint p = new GPoint(0, 0);
int outputWidth = mybitmap.Width;
int outputHeight = mybitmap.Height;
System.Drawing.Imaging.BitmapData bits = mybitmap.LockBits(new Rectangle(0, 0, mybitmap.Width, mybitmap.Height), System.Drawing.Imaging.ImageLockMode.WriteOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
GL.ReadPixels((int)p.X, (int)p.Y, outputWidth, outputHeight, OpenTK.Graphics.OpenGL.PixelFormat.Bgra, PixelType.UnsignedByte, bits.Scan0);
mybitmap.UnlockBits(bits);
//mybitmap.RotateFlip(RotateFlipType.Rotate180FlipX);
mybitmap.Save(#"c:\Downloads\aaa\ReadPixels_" + DateTime.Now.ToString("HHmmss_fff") + ".png", System.Drawing.Imaging.ImageFormat.Png);
pob.masterBitmap.Dispose();
pob.masterBitmap = null;
pob.masterBitmap = (Bitmap)mybitmap.Clone();
}
}
// Unload and dispose the frame buffer
GL.Ext.BindFramebuffer(FramebufferTarget.FramebufferExt, 0);
// Clean up what we allocated before exiting
if (ColorTexture != 0)
GL.DeleteTextures(1, ref ColorTexture);
ColorTexture = 0;
if (DepthTexture != 0)
GL.DeleteTextures(1, ref DepthTexture);
DepthTexture = 0;
if (FBOHandle != 0)
GL.Ext.DeleteFramebuffers(1, ref FBOHandle);
FBOHandle = 0;
}
}
How to get rendered image even if this is not currently rendered on screen?
Create a new frame buffer, bind that frame buffer, set up viewport, set up ortho projection matrix, render your desired piece of the map into it, call GL.ReadPixels, save screenshot, unload and dispose the framebuffer.
Here's some sample code:
// Create framebuffer
int fboId = GL.GenFramebuffer();
GL.BindFramebuffer(FramebufferTarget.Framebuffer, fboId);
// Set up a framebuffer attachment here
int width = ...
int height = ...
int textureId = GL.GenTexture();
GL.BindTexture(TextureTarget.Texture2D, textureId);
GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba8, width, height, 0, PixelFormat.Rgba, PixelType.Float, IntPtr.Zero);
GL.FramebufferTexture2D(FramebufferTarget.Framebuffer, (FramebufferAttachment)fbAtt.AttachmentType, TextureTarget.Texture2D, textureId, 0);
GL.DrawBuffers(1, new int[] { textureId });
GL.Viewport(0, 0, width, height);
// Set up ortho modo. probably also want to disable depth testing and any active blend modes
....
// Render your map now
....
// Grab your screenshot
....
// Unload and dispose the frame buffer
...
// Reset everything (viewport, ortho mode, etc.) if you don't your normal map to flicker for a frame
....
Your other question I don't quite understand
i have a problem with this code :
i need to screenshot the full screen that i see with all things (taskbar, anything open).
my code is just giving me a cropped pic of just one window
Bitmap bitmap = new Bitmap(Screen.PrimaryScreen.Bounds.Width,
Screen.PrimaryScreen.Bounds.Height);
Graphics graphics = Graphics.FromImage(bitmap as Image);
graphics.CopyFromScreen(0, 0, 0, 0, bitmap.Size);
bitmap.Save("D://Changes.jpg", ImageFormat.Jpeg);
Your display settings are set to 125% (or higher) zoom.
Your application isn't DPI aware. You can correct that by updating your application's manifest.
If that doesn't work for you (or you'd rather not use the manifest), you can pinvoke GetDeviceCaps API to get the correct width and height for CopyFromScreen.
Here are your native definitions:
private static class Win32Native
{
public const int DESKTOPVERTRES = 0x75;
public const int DESKTOPHORZRES = 0x76;
[DllImport("gdi32.dll")]
public static extern int GetDeviceCaps(IntPtr hDC, int index);
}
And you'd call it as so:
int width, height;
using(var g = Graphics.FromHwnd(IntPtr.Zero))
{
var hDC = g.GetHdc();
width = Win32Native.GetDeviceCaps(hDC, Win32Native.DESKTOPHORZRES);
height = Win32Native.GetDeviceCaps(hDC, Win32Native.DESKTOPVERTRES);
g.ReleaseHdc(hDC);
}
using (var img = new Bitmap(width, height))
{
using (var g = Graphics.FromImage(img))
{
g.CopyFromScreen(0, 0, 0, 0, img.Size);
}
img.Save(#"C:\users\andy\desktop\test.jpg", ImageFormat.Jpeg);
}
I'm trying to make an image cropping tool.
I am following this https://www.codeproject.com/Articles/703519/Cropping-Particular-Region-In-Image-Using-Csharp
But since it's a bit old and the plugin/DLL's it uses have changed I have been trying to adapt his code from OpenCvSharp 2.0 to OpenCvSharp 2.4
When I'm converting the bitmaps to IplImages and using Cv.Mul() it gives me this error:
Attempted to read or write protected memory. This is often an indication that other memory is corrupt
I have never used OpenCvSharp other ways of creating the IplImage even reading the IplImage from a written image.
Code:
public static IplImage BitmapToIplImage(Bitmap bitmap)
{
IplImage tmp, tmp2;
System.Drawing.Rectangle bRect = new System.Drawing.Rectangle(new System.Drawing.Point(0, 0), new System.Drawing.Size((int)bitmap.Width, (int)bitmap.Height));
BitmapData bmData = bitmap.LockBits(bRect, ImageLockMode.ReadWrite, bitmap.PixelFormat);
tmp = Cv.CreateImage(Cv.Size(bitmap.Width, bitmap.Height), BitDepth.U8, 3);
tmp2 = Cv.CreateImage(Cv.Size(bitmap.Width, bitmap.Height), BitDepth.U8, 1);
byte[] data = new byte[Math.Abs(bmData.Stride * bmData.Height)];
tmp.SetData(bmData.Scan0, data.Length);
bitmap.UnlockBits(bmData);
// Cv.CvtColor(tmp, tmp2, ColorConversion.RgbToGray);
return tmp;
}
private void CropImage()
{
IplImage ipl = Cv.CreateImage(new CvSize(curBmp.Width, curBmp.Height), BitDepth.U8, 3);
Graphics ga = Graphics.FromImage(curBmp);
ga.FillRectangle(new SolidBrush(System.Drawing.Color.Black), new System.Drawing.Rectangle(0, 0, curBmp.Width, curBmp.Height));
SolidBrush brush = new SolidBrush(System.Drawing.Color.FromArgb(1, 1, 1));
curGraphics.FillClosedCurve(brush, imagePoints.ToArray());
Cv.Mul(BitmapToIplImage(curOgBmp), BitmapToIplImage(curBmp), ipl, 1);
ComputeCrop();
Stream s = null;
ipl.ToStream(s, ".png", null);
curBmp = new Bitmap(s);
RefreshImageViewer();
}
-----------------------------EDIT-----------------------------------------
I tried to follow what Markus posted, and I got it to work without any errors in the code.
Although the image cropped is a bit strange here are the methods I use, plus the RefreshImageViewer that is how I put the bitmap in the image control.
I have been trying to see if I missed something for hours, but I think not.
Output example: Imgur image link
Code:
public void RefreshImageViewer()
{
bmpSource = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
curBmp.GetHbitmap(),
IntPtr.Zero,
System.Windows.Int32Rect.Empty,
BitmapSizeOptions.FromWidthAndHeight(curBmp.Width, curBmp.Height));
imageViewer.Source = bmpSource;
curGraphics = Graphics.FromImage(curBmp);
}
private void CropImage()
{
Graphics Ga = Graphics.FromImage(curBmp);
//the black image
Ga.FillRectangle(new SolidBrush(System.Drawing.Color.Black), new System.Drawing.Rectangle(0, 0, curBmp.Width, curBmp.Height));
//draw from the last point to first point
Ga.DrawLine(new System.Drawing.Pen(System.Drawing.Color.Red, 3), imagePoints[imagePoints.Count - 1], imagePoints[0]);
//all of the rgb values are being set 1 inside the polygon
SolidBrush Brush = new SolidBrush(System.Drawing.Color.FromArgb(1, 1, 1));
//we have to prepare one mask of Multiplying operation for cropping region
curGraphics.FillPolygon(Brush, imagePoints.ToArray());
Mat accc = (BitmapToMat(curOgBmp).Mul(BitmapToMat(curBmp))).ToMat();
System.Drawing.Rectangle r = ComputeCrop();
curBmp = accc.ToBitmap().Clone(r, curOgBmp.PixelFormat);
RefreshImageViewer();
}
private System.Drawing.Rectangle ComputeCrop()
{
int smallestX = curBmp.Width, biggestX = 0, biggestY = 0, smallestY = curBmp.Height;
for (int i = 0; i < imagePoints.Count; i++)
{
biggestX = Math.Max(biggestX, imagePoints[i].X);
smallestX = Math.Min(smallestX, imagePoints[i].X);
biggestY = Math.Max(biggestY, imagePoints[i].Y);
smallestY = Math.Min(smallestY, imagePoints[i].Y);
}
System.Drawing.Rectangle rectCrop = new System.Drawing.Rectangle(smallestX, smallestY, biggestX - smallestX, biggestY - smallestY);
return rectCrop;
}
public static Mat BitmapToMat(Bitmap bitmap)
{
Mat tmp, tmp2;
System.Drawing.Rectangle bRect = new System.Drawing.Rectangle(new System.Drawing.Point(0, 0), new System.Drawing.Size((int)bitmap.Width, (int)bitmap.Height));
BitmapData bmData = bitmap.LockBits(bRect, ImageLockMode.ReadWrite, bitmap.PixelFormat);
tmp2 = new Mat(new OpenCvSharp.Size(bitmap.Width, bitmap.Height), MatType.CV_8U);
tmp = new Mat(bitmap.Height, bitmap.Width, MatType.CV_8UC3, bmData.Scan0);
bitmap.UnlockBits(bmData);
return tmp;
}
“IplImage” ist the old image container from OpenCv 1. As Andreas already mentioned, today you should use “Mat” instead. Have also a look here : Difference between cvMat, Mat and IpImage
Unfortunately, your code sample is not complete, hence I corrected the two methods from the original project ( https://www.codeproject.com/Articles/703519/Cropping-Particular-Region-In-Image-Using-Csharp).
The following methods are tested and work as intended in the original project in combination with the latest OpenCVSharp version (v4.x) . It should be very simple now to convert the changes to your code.
public static Mat BitmapToIplImage(Bitmap bitmap)
{
Mat tmp, tmp2;
Rectangle bRect = new Rectangle(new System.Drawing.Point(0, 0), new System.Drawing.Size((int)bitmap.Width, (int)bitmap.Height));
BitmapData bmData = bitmap.LockBits(bRect, ImageLockMode.ReadWrite, bitmap.PixelFormat);
tmp2 = new Mat(new Size(bitmap.Width, bitmap.Height), MatType.CV_8U);
tmp = new Mat(bitmap.Height, bitmap.Width, MatType.CV_8UC3, bmData.Scan0);
bitmap.UnlockBits(bmData);
return tmp;
}
private void crop()
{
timer1.Stop();
Graphics Ga = Graphics.FromImage(bmp);
//the black image
Ga.FillRectangle(new SolidBrush(Color.Black), new Rectangle(0, 0, bmp.Width, bmp.Height));
//draw from the last point to first point
Ga.DrawLine(new Pen(Color.Red, 3), polygonPoints[polygonPoints.Count - 1], polygonPoints[0]);
//all of the rgb values are being set 1 inside the polygon
SolidBrush Brush = new SolidBrush(Color.FromArgb(1, 1, 1));
//we have to prepare one mask of Multiplying operation for cropping region
G.FillClosedCurve(Brush, polygonPoints.ToArray());
var accc= (BitmapToIplImage(Source).Mul(BitmapToIplImage(bmp))).ToMat();
computecrop();
croplast = accc.ToBitmap().Clone(rectcrop, Source.PixelFormat);//just show cropped region part of image
pictureBox2.Image = croplast; // crop region of image
}
This seems like it should be simple, but I can't seem to find any way to do it. I have a custom WinForms control that has an overridden paint method that does some custom drawing.
I have a Bitmap in memory, and all I want to do is paint over the whole thing with a HashBrush, but preserve the alpha channel, so that the transparent parts of the bitmap don't get painted.
The bitmap in memory is not a simple shape, so it will not be feasible to define it as a set of paths or anything.
EDIT: In response to showing the code, there is a lot of code in the paint routine, so I'm only including a relevant snippet, which is the method in question. This method gets called from the main paint override. It accepts a list of images which are black transparency masks and combines them into one, then it uses a ColorMatrix to change the color of the combined image it created, allowing it to be overlayed on top of the background. All I want to accomplish is being able to also paint hashmarks on top of it.
private void PaintSurface(PaintEventArgs e, Image imgParent, List<Image> surfImgs, Rectangle destRect, ToothSurfaceMaterial material)
{
using (Bitmap bmp = new Bitmap(imgParent.Width, imgParent.Height,
System.Drawing.Imaging.PixelFormat.Format32bppPArgb))
{
using (Graphics g = Graphics.FromImage(bmp))
{
foreach (Image img in surfImgs)
{
g.DrawImage(img, System.Drawing.Point.Empty);
}
}
ColorMatrix matrix = new ColorMatrix(
new float[][] {
new float[] { 0, 0, 0, 0, 0},
new float[] { 0, 0, 0, 0, 0},
new float[] { 0, 0, 0, 0, 0},
new float[] { 0, 0, 0, 0.7f, 0},
new float[] { material.R / 255.0f,
material.G / 255.0f,
material.B / 255.0f,
0, 1}
});
ImageAttributes imageAttr = new ImageAttributes();
imageAttr.SetColorMatrix(matrix);
Rectangle r = GetSizedRect(imgParent, destRect);
e.Graphics.DrawImage(bmp,
r,
0,
0,
bmp.Width,
bmp.Height,
GraphicsUnit.Pixel, imageAttr);
}
}
The solution I ended up using was the following method. First I combine the individual masks into one, then create a new Bitmap and paint the whole thing with the HatchBrush, finally iterate through the mask and set the alpha values on the newly generated bitmap based on the mask.
private Bitmap GenerateSurface(Image imgParent, List<Image> surfImgs, ToothSurfaceMaterial material)
{
Bitmap mask = new Bitmap(imgParent.Width, imgParent.Height,
System.Drawing.Imaging.PixelFormat.Format32bppPArgb);
using (Graphics g = Graphics.FromImage(mask))
{
foreach (Image img in surfImgs)
{
g.DrawImage(img, System.Drawing.Point.Empty);
}
}
Bitmap output = new Bitmap(mask.Width, mask.Height,
System.Drawing.Imaging.PixelFormat.Format32bppPArgb);
using (Graphics g = Graphics.FromImage(output))
{
if (material.HatchStyle != null)
{
HatchBrush hb = new HatchBrush((HatchStyle)material.HatchStyle, material.FgColor, material.BgColor);
g.FillRectangle(hb, new Rectangle(0, 0, output.Width, output.Height));
}
else
{
SolidBrush sb = new SolidBrush(material.FgColor);
g.FillRectangle(sb, new Rectangle(0, 0, output.Width, output.Height));
}
}
var rect = new Rectangle(0, 0, output.Width, output.Height);
var bitsMask = mask.LockBits(rect, ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
var bitsOutput = output.LockBits(rect, ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
unsafe
{
int offset = 0;
for (int y = 0; y < mask.Height; y++)
{
byte* ptrMask = (byte*)bitsMask.Scan0 + y * bitsMask.Stride;
byte* ptrOutput = (byte*)bitsOutput.Scan0 + y * bitsOutput.Stride;
for (int x = 0; x < mask.Width; x++)
{
offset = 4 * x + 3;
ptrOutput[offset] = (byte)(ptrMask[offset] * 0.7);
}
}
}
mask.UnlockBits(bitsMask);
output.UnlockBits(bitsOutput);
return output;
}
I think you don't need any ColorMatrix which is overkill, you just need a ColorMap, here is the code which may not suit your requirement but should give you the idea. That's because I possibly don't understand your problem well, if you have any problem, just leave some comment and I'll try to improve the answer:
ImageAttributes imgA = new ImageAttributes();
ColorMap cm = new ColorMap();
cm.OldColor = Color.Black
cm.NewColor = Color.FromArgb((byte)(0.7*255), Color.Green);
imgA.SetRemapTable(new ColorMap[] {cm });
GraphicsUnit gu = GraphicsUnit.Pixel;
g.DrawImage(imageToDraw,new Point[]{Point.Empty,
new Point(backImage.Width/2,0),
new Point(0,backImage.Height/2)},
Rectangle.Round(imageToDraw.GetBounds(ref gu)),
GraphicsUnit.Pixel, imgA);
the new Point[] is an array of 3 Points used to locate the destination Rectangle.
The code above is used to Draw the imageToDraw on top of the backImage and convert and color of Black to the color Green with Opacity = 70%. That's what you want to fulfill your code.
UPDATE
This may be what you want, in fact your code doesn't show what you want, it just shows what you have which doesn't implement anything related to your problem now. I deduce this from your very first description in your question. The input is an image with background color (which will be made partially transparent later) being Black. Now the output you want is an image with all the non-Black region being painted with a HatchBrush. This output will then be processed to turn the Black background to a partially transparent background.
public void PaintHatchBrush(Bitmap input, HatchBrush brush){
using(Graphics g = Graphics.FromImage(input)){
g.Clip = GetForegroundRegion(input, Color.Black);
GraphicsUnit gu = GraphicsUnit.Pixel;
g.FillRectangle(brush, input.GetBounds(ref gu));
}
}
//This is implemented using `GetPixel` which is not fast, but it gives you the idea.
public Region GetForegroundRegion(Bitmap input, Color backColor){
GraphicsPath gp = new GraphicsPath();
Rectangle rect = Rectangle.Empty;
bool jumpedIn = false;
for (int i = 0; i < bm.Height; i++) {
for (int j = 0; j < bm.Width; j++) {
Color c = bm.GetPixel(j, i);
if (c != backColor&&!jumpedIn) {
rect = new Rectangle(j, i, 1, 1);
jumpedIn = true;
}
if (jumpedIn && (c == backColor || j == bm.Width - 1)) {
rect.Width = j - rect.Left;
gp.AddRectangle(rect);
jumpedIn = false;
}
}
}
return new Region(gp);
}
//Usage
HatchBrush brush = new HatchBrush(HatchStyle.Percent30, Color.Green, Color.Yellow);
PaintHatchBrush(yourImage, brush);
//then yourImage will have HatchBrush painted on the surface leaving the Black background intact.
//This image will be used in the next process to turn the Black background into 70%
//opacity background as you did using ColorMatrix (or more simply using ColorMap as I posted previously)
I am trying to use DrawThemeBackground to draw to a bitmap in C#, but it always comes out as black.
Bitmap bmp = new Bitmap(this.Width, this.Height, PixelFormat.Format32bppArgb);
using (Graphics g = Graphics.FromImage(bmp))
{
g.Clear(Color.Green);
IntPtr hdc = g.GetHdc();
DrawThemeBackground(hTheme, hdc, 0, 1, ref rect, IntPtr.Zero);
g.ReleaseHdc(hdc);
}
It appears that DrawThemeBackground isn't looking at the background colour of the bitmap (green in this case) and is always blending with black. Am I missing something here? Is this even possible to do?