TGA Encoder/Decoder Improvements #2197
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… Packet otherwise
| { | ||
| var alpha = alphaBits == 0 ? byte.MaxValue : bufferSpan[idx + 3]; | ||
| color.FromBgra32(new Bgra32(bufferSpan[idx + 2], bufferSpan[idx + 1], bufferSpan[idx], (byte)alpha)); | ||
| byte alpha = alphaBits == 0 ? byte.MaxValue : bufferSpan[idx + 3]; |
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Why do we use Bgra here when the buffer is Rgba?
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Because of the Intel byte ordering, the data needs to be interpreted as bgra. Quote from the Spec:
| Image Data Field. |
| |
| This field specifies (width) x (height) pixels. Each |
| pixel specifies an RGB color value, which is stored as |
| an integral number of bytes. |
| The 2 byte entry is broken down as follows: |
| ARRRRRGG GGGBBBBB, where each letter represents a bit. |
| But, because of the lo-hi storage order, the first byte |
| coming from the file will actually be GGGBBBBB, and the |
| second will be ARRRRRGG. "A" represents an attribute bit. |
| The 3 byte entry contains 1 byte each of blue, green, |
| and red. |
| The 4 byte entry contains 1 byte each of blue, green, |
| red, and attribute. For faster speed (because of the |
| hardware of the Targa board itself), Targa 24 images are |
| sometimes stored as Targa 32 images. |
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Thanks... I was thrown by the assignment order in the Bgra32 constructor. Forgot the order was r,g,b,a.
This was referenced Sep 29, 2025
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Prerequisites
Description
This is a follow up PR for #2172. It does a few things: