Welcome : GDI+ FAQ

Welcome to the GDI+ FAQ

GDI+ is a native C++ DLL that was originally created for the Microsoft Office suite. It has graphical capabilities that were far in advance of the original Windows graphics system, GDI. For .Net, and particularly Windows Forms, GDI+ was given a managed wrapper that enabled it to be used with C# and VB.Net. For many years GDI+ has provided a sterling service, enabling Windows Forms applications to show really great graphics. Unfortunately, the adoption of GDI+ never really sparked the imaginations of the graphics card manufacturers and therefore hardware acelleration was only provided by a few graphics cards from the Matrox corporation. Because GDI+ never took off as a serious games graphics engine, the manufacurers preferred to concentrate on the capabilities of DirectX.

This list of articles that began on another site in 2001 contains many real world examples of how to get the best from GDI+. Enjoy!

FAQ

The #1 most asked GDI+ question Why do my graphics keep disappearing? Images Creating and loading images Drawing Images Calculating best-fit drawing using a transform Convert color images to grayscale Changing resolution of or cropping images Saving JPEG images with a specific compression quality Creating animated GIF images Creating a negative image Modifying an image and writing it back to the same filename Converting RGB to 1 bit-per-pixel monochrome Transparent GIF images Discovering the Property Items present in an image Understanding the LockBits method and the BitmapData class Creating high-resolution images and text Creating an optimized palette for GIF images Generating Multi-Frame TIFF image files Adding frames to a Multi-Frame TIFF Drawing on an existing image Creating a high-quality thumbnail image Colour Using RGB and HSL in .NET Adjusting the Saturation of an image Adjusting the contrast of an image Finding the colour at a certain point. (eyedropper) Text Drawing text with a drop-shadow Text effects. Emboss, Outline and Warp Drawing text at an angle Drawing text on a reversed Y axis Drawing text with a halo or aura Formatting text on a common baseline Drawing lines and shapes Drawing single pixel lines Plotting single pixels Drawing round rectangles Hit testing lines Pens and brushes Using the LinearGradientBrush Using the PathGradientBrush Scaling the TextureBrush Scaling the Pen object Paths Hit testing lines Regions Extract a region from a bitmap General GDI+ technique When to dispose of resources Converting mouse coordinates to the current page units Comparing GDI Mapping Modes and GDI+ Transformations Miscellaneous questions and tips Why is GDI+ so slow? How (or how not) to use the PictureBox control How do I manipulate the graphics on screen? How to capture the screen or an image of a control When to use CreateGraphics What are the limits of the drawing extents? BUGS! The Spirograph bug GetRegionScans BUG

Bob Powell

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