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https://github.com/SerenityOS/serenity
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66bdb3bf43
Previously, the order of data was incorrectly based on x_origin and
y_origin, which are meant for where on the screen the image should be
placed (TarGA is an image format meant for graphic cards), instead of
Image descriptor bits 4 and 5, which specify the direction.
This fixes a problem where tga files generated with magick would render
up-side-down.
The test images where created in GIMP, 4 simple 2x2 images
exported as .tga, no compression, origin: Bottom Left
square-bottom-left.tga:
Red, Green
Blue, Magenta
square-bottom-right.tga:
Green, Red
Magenta, Blue
square-top-left.tga:
Blue, Magenta
Red, Green
square-top-right.tga:
Magenta, Blue
Green, Red
then this script was ran:
```python
def update_tga_descriptor(file_path, top_to_bottom, left_to_right):
with open(file_path, 'r+b') as f:
header = f.read(18)
descriptor = header[17]
descriptor &= ~(1 << 4);
descriptor &= ~(1 << 5);
if left_to_right:
descriptor |= 1 << 4;
if top_to_bottom:
descriptor |= 1 << 5;
header = header[:17] + bytes([descriptor])
f.seek(0)
f.write(header)
update_tga_descriptor('square-bottom-left.tga', False, False)
update_tga_descriptor('square-bottom-right.tga', False, True)
update_tga_descriptor('square-top-left.tga', True, False)
update_tga_descriptor('square-top-right.tga', True, True)
```
