iOS fractional crop coordinates cause an incorrect byte offset

[dodokw]

@mrousavy

Summary

Fix incorrect iOS cropping when the calculated crop rectangle contains fractional values.

• Convert crop origins and dimensions to integral pixel values before pointer arithmetic.
• Prevent a fractional cropY from becoming an unintended in-row byte offset.
• Keep the source pointer aligned to whole-pixel coordinates.

Fixes #

Root cause

When no explicit crop is provided, the automatic center-crop calculation can produce fractional coordinates.

For example, resizing a 640x480 frame to 576x320 calculates approximately:

• cropHeight = 355.555
• cropY = 62.222

Previously, iOS kept these values as CGFloat and converted only the final byte-offset expression to size_t:

cropY * rowBytes + cropX * bytesPerPixel