Perf: Convert only the required source region in DrawImage#407
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christianrondeau wants to merge 1 commit into
Open
Perf: Convert only the required source region in DrawImage#407christianrondeau wants to merge 1 commit into
christianrondeau wants to merge 1 commit into
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Prerequisites
Description
While testing for performance improvement opportunities, I noticed that using the Draw API with an Image onto an Image, ALL pixels of the source image were converted before drawing (https://github.com/SixLabors/ImageSharp.Drawing/blob/main/src/ImageSharp.Drawing/Processing/DrawingCanvas%7BTPixel%7D.cs#L665).
This PR crops the source first and converts the cropped region after.
Impact
Measured on a 22.9 MP image (5700×4014), drawing a 1/8-area region using a custom MemoryAllocator for measuring:
Before: 103MB, 24.4ms (4.3x less memory)
After: 24MB, 14.4 ms (1.7x faster)
NOTE: This also fixes a small leak, this clone was never disposed: https://github.com/SixLabors/ImageSharp.Drawing/blob/main/src/ImageSharp.Drawing/Processing/DrawingCanvas%7BTPixel%7D.cs#L665