Renderer Base

AGG uses agg::renderer_base to handle most of operations. It contains all the information needed regarding the image metadata and buffering.

You will need the following parts before creating a agg::renderer_base.

• a raw image byte buffer.
• a agg::rendering_buffer that wraps around the byte buffer with width, height, and x-stride information.
• pixel format which specifies the pixel color format.

typedef agg::pixfmt_rgba32  PixelFormat;
typedef agg::renderer_base<PixelFormat> RendererBaseType;

const int pixelSize = PixelFormat::pix_width;

agg::rendering_buffer   renderBuffer;
PixelFormat             pixFmt;
RendererBaseType        rBase;

// Allocate a 100 x 100 rgba buffer
unsigned char *imageBuffer = new unsigned char[imageWidth * imageHeight * pixelSize];

// Hook everything up
renderBuffer.attach (imageBuffer, imageWidth, imageHeight, imageWidth * pixelSize);
pixFmt.attach(renderBuffer);
rBase.attach(pixFmt);

Example

See tutorial_rendererbase.cpp for an example of constructing an RGBA renderer_base. It also shows how to do direct pixel manipulations using renderer_base. In this example, a simple green border is drawn. The output is saved to an PNG.