/// <summary>
        /// Special draw logic to draw transparent text using GDI.<br/>
        /// 1. Create in-memory DC<br/>
        /// 2. Copy background to in-memory DC<br/>
        /// 3. Draw the text to in-memory DC<br/>
        /// 4. Copy the in-memory DC to the proper location with alpha blend<br/>
        /// </summary>
        static void DrawTransparentText(IntPtr hdc, string str, Font font, Point point, Size size, Color color)
        {
            IntPtr dib;
            var    memoryHdc = Win32Utils.CreateMemoryHdc(hdc, size.Width, size.Height, out dib);

            try
            {
                // copy target background to memory HDC so when copied back it will have the proper background
                Win32Utils.BitBlt(memoryHdc, 0, 0, size.Width, size.Height, hdc, point.X, point.Y, Win32Utils.BitBltCopy);

                // Create and select font
                Win32Utils.SelectObject(memoryHdc, FontStore.GetCachedHFont(font.InnerFont as System.Drawing.Font));
                Win32Utils.SetTextColor(memoryHdc, (color.B & 0xFF) << 16 | (color.G & 0xFF) << 8 | color.R);

                // Draw text to memory HDC
                NativeTextWin32.TextOut(memoryHdc, 0, 0, str, str.Length);

                // copy from memory HDC to normal HDC with alpha blend so achieve the transparent text
                Win32Utils.AlphaBlend(hdc, point.X, point.Y, size.Width, size.Height, memoryHdc, 0, 0, size.Width, size.Height, new BlendFunction(color.A));
            }
            finally
            {
                Win32Utils.ReleaseMemoryHdc(memoryHdc, dib);
            }
        }
        /// <summary>
        /// Set a resource (e.g. a font) for the specified device context.
        /// WARNING: Calling Font.ToHfont() many times without releasing the font handle crashes the app.
        /// </summary>
        void SetFont(Font font)
        {
            InitHdc();

            Win32Utils.SelectObject(tempDc, FontStore.GetCachedHFont(font.InnerFont as System.Drawing.Font));
        }
Ejemplo n.º 3
0
 float IFonts.MeasureWhitespace(PixelFarm.Drawing.Font f)
 {
     return(FontStore.MeasureWhitespace(this, f));
 }