Lecture_8_Pycairo_Images_Surfaces---.pptx

Lecture 8

1. Lecture 8: Images and Surfaces in Pycairo Understanding surfaces, image handling, and exporting results.

2. What are Surfaces? - A Surface is the target for all drawing operations - Types: • ImageSurface (PNG raster images) • PDFSurface (PDF export) • SVGSurface (vector graphics) • Win32/XlibSurface (platform-specific)

3. Creating an Image Surface import cairo surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, 400, 300) context = cairo.Context(surface) context.set_source_rgb(1, 1, 1) context.paint() surface.write_to_png('output.png')

4. Drawing Shapes on Image Surfaces context.set_source_rgb(1, 0, 0) context.rectangle(50, 50, 200, 100) context.fill() surface.write_to_png('shapes.png')

5. Loading and Drawing External Images img_surface = cairo.ImageSurface.create_from_png('logo.png') context.set_source_surface(img_surface, 100, 100) context.paint() surface.write_to_png('combined.png')

6. Scaling Images context.save() context.translate(50, 50) context.scale(0.5, 0.5) context.set_source_surface(img_surface, 0, 0) context.paint() context.restore()

7. Using Multiple Surfaces temp_surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, 200, 200) temp_ctx = cairo.Context(temp_surface) temp_ctx.set_source_rgb(0, 0, 1) temp_ctx.arc(100, 100, 80, 0, 6.28) temp_ctx.fill() context.set_source_surface(temp_surface, 150, 50) context.paint() surface.write_to_png('multi_surface.png')

8. Saving to Different Formats pdf_surface = cairo.PDFSurface('output.pdf', 400, 300) pdf_ctx = cairo.Context(pdf_surface) pdf_ctx.set_source_rgb(0, 0, 0) pdf_ctx.move_to(50, 50) pdf_ctx.show_text('Hello PDF!') pdf_surface.finish()

9. Summary - Surfaces are the target for all drawing - ImageSurface is most common for PNG output - You can load, scale, and combine images - Export drawings to PNG, PDF, or SVG