Develop Reference

How do I write text on WriteableBitmap?

Right now I'm coding a game and I need to draw text onto a WriteableBitmap; how do I do this without converting from WritableBitmap to Bitmap to WriteableBitmap? I've searched for solutions already, but all of them slow down my game or need something like Silverlight to work.
something like this:
public class ResourceCounter : UIElement
{
public ResourceCounter()
{
RenderBounds = new Bound(new Point(0, 0),
new Point(600, 30));
}
private string goldAmt;
private string woodAmt;
private string stoneAmt;
public override void Tick()
{
goldAmt = GlobalResources.Gold.ToString();
woodAmt = GlobalResources.Wood.ToString();
stoneAmt = GlobalResources.Stone.ToString();
}
public override void Draw(WriteableBitmap bitmap)
{
bitmap.FillRectangle(RenderBounds.A.X,
Renderbounds.A.Y,
Renderbounds.B.X,
Renderbounds.B.Y,
Colors.DarkSlateGray);
bitmap.DrawString("text", other parameters...");
}
}

You can share the Pixel buffer between a Bitmap and a BitmapSource
var writeableBm1 = new WriteableBitmap(200, 100, 96, 96,
System.Windows.Media.PixelFormats.Bgr24, null);
var w = writeableBm1.PixelWidth;
var h = writeableBm1.PixelHeight;
var stride = writeableBm1.BackBufferStride;
var pixelPtr = writeableBm1.BackBuffer;
// this is fast, changes to one object pixels will now be mirrored to the other
var bm2 = new System.Drawing.Bitmap(
w, h, stride, System.Drawing.Imaging.PixelFormat.Format24bppRgb, pixelPtr);
writeableBm1.Lock();
// you might wanna use this in combination with Lock / Unlock, AddDirtyRect, Freeze
// before you write to the shared Ptr
using (var g = System.Drawing.Graphics.FromImage(bm2))
{
g.DrawString("MyText", new Font("Tahoma", 14), System.Drawing.Brushes.White, 0, 0);
}
writeableBm1.AddDirtyRect(new Int32Rect(0, 0, 200, 100));
writeableBm1.Unlock();

How to overlay two picturebox c# but the picturebox in the background can be seen

Good day
i don't know if my title is correct. sorry for my bad english
How to overlay two picturebox using c# inoder to achieve the image below, and change the opacity of upper picture box on runtime.
what i need to achieve is something like this. i have two images and i need to overlay them
first image:
enter image description here
and i have second image with a text of: Another Text on image.
and the location of the text is lower than the text location of the first image
(i can't upload more than two image because i don't have 10 reputation yet.)
i need to do like on the image below, but using two picturebox and can change the opacity in order for the second picturebox below the first one to be seen
and the output of the two image:
enter image description here
i created the output image using java. i know that i can run the jar file using c#. but the user required to changed the opacity on run time. so how can i do this?
this is the java code i used
BufferedImage biInner = ImageIO.read(inner);
BufferedImage biOutter = ImageIO.read(outter);
System.out.println(biInner);
System.out.println(biOutter);
Graphics2D g = biOutter.createGraphics();
g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f));
int x = (biOutter.getWidth() - biInner.getWidth()) / 2;
int y = (biOutter.getHeight() - biInner.getHeight()) / 2;
System.out.println(x + "x" + y);
g.drawImage(biInner, x, y, null);
g.dispose();
ImageIO.write(biOutter, "PNG", new File(output));
i hope my question is understandable. thank you

Here you go, just a sample, but blueBox is transparent (0.5):
public sealed partial class Form1 : Form
{
private readonly Bitmap m_BlueBox;
private readonly Bitmap m_YellowBox;
public Form1()
{
InitializeComponent();
DoubleBuffered = true;
m_YellowBox = CreateBox(Color.Yellow);
m_BlueBox = CreateBox(Color.Blue);
m_BlueBox = ChangeOpacity(m_BlueBox, 0.5f);
}
public static Bitmap ChangeOpacity(Image img, float opacityvalue)
{
var bmp = new Bitmap(img.Width, img.Height);
using (var graphics = Graphics.FromImage(bmp))
{
var colormatrix = new ColorMatrix();
colormatrix.Matrix33 = opacityvalue;
var imgAttribute = new ImageAttributes();
imgAttribute.SetColorMatrix(colormatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
graphics.DrawImage(img, new Rectangle(0, 0, bmp.Width, bmp.Height), 0, 0, img.Width, img.Height,
GraphicsUnit.Pixel, imgAttribute);
}
return bmp;
}
private static Bitmap CreateBox(Color color)
{
var bmp = new Bitmap(200, 200);
for (var x = 0; x < bmp.Width; x++)
{
for (var y = 0; y < bmp.Height; y++)
{
bmp.SetPixel(x, y, color);
}
}
return bmp;
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawImage(m_YellowBox, new Point(10, 10));
e.Graphics.DrawImage(m_BlueBox, new Point(70, 70));
}
}

Change alpha coefficient using Lockbits

I have written a function which changes the alpha coefficient of an image. I use setpixel and getpixel,which is very slow. I found out that Lockbits method is faster.How can I do it with Lockbits?
Here is my current code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace WindowsFormsApplication2
{
public partial class Form1 : Form
{
private static Image Tran(Image s,int alpha)
{
int x = 0, y = 0;
Bitmap tImage = new Bitmap(s);
for (x = 0; x < tImage.Width; x++)
{
for (y = 0; y < tImage.Height; y++)
{
tImage.SetPixel(x, y, Color.FromArgb(alpha, tImage.GetPixel(x, y).R, tImage.GetPixel(x, y).G, tImage.GetPixel(x, y).B));
}
}
return tImage;
}
public Form1()
{
InitializeComponent();
trackBar1.TickStyle = TickStyle.Both;
trackBar1.Orientation = Orientation.Vertical;
trackBar1.Minimum = 0;
trackBar1.Maximum = 255;
trackBar1.Height = 101;
trackBar1.Value = 255;
pictureBox1.Image = Image.FromFile("C:\\Users\\rati\\Desktop\\water.jpg");
pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
}
private void trackBar1_Scroll(object sender, EventArgs e)
{
pictureBox1.Image = ChangeAlpha(pictureBox1.Image, trackBar1.Value);
textBox1.Text = trackBar1.Value.ToString();
}
}
}

You can change the opacity of your image by drawing it in a new bitmap using a new ColorMatrix and assigning a float value between 0 and 1 to its Matrix33 as its new alpha value:
public Image ChangeAlpha(Image img, int value)
{
if (value < 0 || value > 255)
throw new Exception("value must be between 0 and 255");
Bitmap bmp = new Bitmap(img.Width, img.Height); // Determining Width and Height of Source Image
Graphics graphics = Graphics.FromImage(bmp);
ColorMatrix colormatrix = new ColorMatrix();
colormatrix.Matrix33 = value / 255f;
ImageAttributes imgAttribute = new ImageAttributes();
imgAttribute.SetColorMatrix(colormatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
graphics.DrawImage(img, new Rectangle(0, 0, bmp.Width, bmp.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel, imgAttribute);
graphics.Dispose(); // Releasing all resource used by graphics
return bmp;
}
And here is a sample usage:
private void button1_Click(object sender, EventArgs e)
{
int opacityvalue = 127;
var img = ChangeAlpha(Image.FromFile(#"d:\1.png"), opacityvalue);
img.Save(#"d:\2.png");
}
Don't forget to add using System.Drawing; and using System.Drawing.Imaging;.
You can see before and after calling the function with value=127 below:
EDIT
If you want to see the result in a PictureBox you should pay attention to using 2 different picture boxes, one for original image, and one for changed image:
private void trackBar1_Scroll(object sender, EventArgs e)
{
this.pictureBox2.Image = ChangeAlpha(this.pictureBox1.Image, this.trackBar1.Value);
}
As I see in your code when you change the opacity, you set the result as image of your PictureBox1 again and apply opacity again on the result. In other word you apply opacity on an image that you applied opacity to it before over and over again.

public Form1()
{
...
originalImage = new Bitmap("C:\\Users\\rati\\Desktop\\water.jpg");
pictureBox1.Image = originalImage;
...
}
// Add an extra field to the Form class.
Bitmap originalImage;
void trackBar1_Scroll(object sender, EventArgs e)
{
pictureBox1.Image = ChangeAlpha((byte)trackBar1.Value);
textBox1.Text = trackBar1.Value.ToString();
}
Image ChangeAlpha(byte alpha)
{
Bitmap bmp = new Bitmap(originalImage);
Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
BitmapData bmpData = bmp.LockBits(rect, ImageLockMode.ReadWrite, bmp.PixelFormat);
IntPtr ptr = bmpData.Scan0;
int bytes = Math.Abs(bmpData.Stride) * bmp.Height;
byte[] rgbValues = new byte[bytes];
Marshal.Copy(ptr, rgbValues, 0, bytes);
// Set every fourth value to alpha. A 32bpp bitmap will change transparency.
for (int counter = 3; counter < rgbValues.Length; counter += 4)
rgbValues[counter] = alpha;
// Also you can try parallelize loop.
//int length = rgbValues.Length / 4;
//Parallel.For(3, length, counter => rgbValues[counter * 4 - 1] = alpha);
Marshal.Copy(rgbValues, 0, ptr, bytes);
bmp.UnlockBits(bmpData);
return bmp;
}

Use Graphic.DrawLines(Pen pen, Points points) for Metafile, the picture cannot open when the count of points is large

I have a problem with a GDI+ metafile. I want to save a metafile by graphic. It works well when the point count is 10000 and the saved metafile can be opened. But when the point count is large (e.g. count = 10000000), the metafile cannot be opened by mspaint.exe.
Is there anything I missed? Is metafile record size limited? By the way, drawrectangles also has this issue.
Here is my code:
private void button1_Click(object sender, EventArgs e)
{
int width = 1489;
int height = 471;
Graphics offScreenBufferGraphics;
Metafile m;
using (MemoryStream stream = new MemoryStream())
{
using (offScreenBufferGraphics = Graphics.FromHwndInternal(IntPtr.Zero))
{
IntPtr deviceContextHandle = offScreenBufferGraphics.GetHdc();
m = new Metafile(
stream,
deviceContextHandle,
new RectangleF(0, 0, width, height),
MetafileFrameUnit.Pixel,
EmfType.EmfPlusOnly);
offScreenBufferGraphics.ReleaseHdc();
}
}
using (Graphics g = Graphics.FromImage(m))
{
// Set everything to high quality
g.SmoothingMode = SmoothingMode.HighQuality;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
g.CompositingQuality = CompositingQuality.HighQuality;
MetafileHeader metafileHeader = m.GetMetafileHeader();
g.ScaleTransform(
metafileHeader.DpiX / g.DpiX,
metafileHeader.DpiY / g.DpiY);
g.PageUnit = GraphicsUnit.Pixel;
g.SetClip(new RectangleF(0, 0, width, height));
// clears the image and colors the entire background
g.Clear(Color.White);
// draw lines
using (Pen pen = new Pen(Color.Black, 1f))
{
Random rnd = new Random(DateTime.Now.Millisecond);
List<PointF> polyPoints = new List<PointF>();
const int count = 10000;
for (int i = 1; i <= 10000000; i++)
{
polyPoints.Add(new PointF(rnd.Next(1000),rnd.Next(1000)));
}
g.DrawLines(pen, polyPoints.ToArray());
// while
} // using
} // using
// Get a handle to the metafile
IntPtr iptrMetafileHandle = m.GetHenhmetafile();
// Export metafile to an image file
CopyEnhMetaFile(iptrMetafileHandle, #"F:\CacheToDisk\test2.emf");
// Delete the metafile from memory
DeleteEnhMetaFile(iptrMetafileHandle);
}
[DllImport("gdi32.dll")]
static extern IntPtr CopyEnhMetaFile( // Copy EMF to file
IntPtr hemfSrc, // Handle to EMF
String lpszFile // File
);
[DllImport("gdi32.dll")]
static extern int DeleteEnhMetaFile( // Delete EMF
IntPtr hemf // Handle to EMF
);

It seems like the limitation. If I use DrawPath instead of DrawLines, it works correctly.

C#: Draw one Bitmap onto Another, with Transparency

I have two Bitmaps, named largeBmp and smallBmp. I want to draw smallBmp onto largeBmp, then draw the result onto the screen. SmallBmp's white pixels should be transparent. Here is the code I'm using:
public Bitmap Superimpose(Bitmap largeBmp, Bitmap smallBmp) {
Graphics g = Graphics.FromImage(largeBmp);
g.CompositingMode = CompositingMode.SourceCopy;
smallBmp.MakeTransparent();
int margin = 5;
int x = largeBmp.Width - smallBmp.Width - margin;
int y = largeBmp.Height - smallBmp.Height - margin;
g.DrawImage(smallBmp, new Point(x, y));
return largeBmp;
}
The problem is that the result winds up transparent wherever smallBmp was transparent! I just want to see through to largeBmp, not to what's behind it.

CompositingMode.SourceCopy is the problem here. You want CompositingMode.SourceOver to get alpha blending.

Specify the transparency color of your small bitmap. e.g.
Bitmap largeImage = new Bitmap();
Bitmap smallImage = new Bitmap();
--> smallImage.MakeTransparent(Color.White);
Graphics g = Graphics.FromImage(largeImage);
g.DrawImage(smallImage, new Point(10,10);

Winform copy image on top of another
private void timerFFTp_Tick(object sender, EventArgs e)
{
if (drawBitmap)
{
Bitmap bitmap = new Bitmap(_fftControl.Width, _fftControl.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
_fftControl.DrawToBitmap(bitmap, new Rectangle(0, 0, _fftControl.Width, _fftControl.Height));
if (!fDraw)
{
bitmap.MakeTransparent();
Bitmap fftFormBitmap = new Bitmap(_fftForm.BackgroundImage);
Graphics g = Graphics.FromImage(fftFormBitmap);
g.DrawImage(bitmap, 0, 0);
_fftForm.BackgroundImage = fftFormBitmap;
}
else
{
fDraw = false;
_fftForm.Width = bitmap.Width + 16;
_fftForm.Height = bitmap.Height + 48;
_fftForm.BackgroundImage = bitmap;
}
}
}