A fork of https://github.com/crosspoint-reader/crosspoint-reader
feat: Scale cover images up if they're smaller than the device resolution (#964)
## Summary
**What is the goal of this PR?**
* Implement feature request
[#954](https://github.com/crosspoint-reader/crosspoint-reader/issues/954)
* Ensure cover images are scaled up to match the dimensions of the
screen, as well as scaled down
**What changes are included?**
* Naïve implementation for scaling up the source image
## Additional Context
If you find the extra comments to be excessive I can pare them back.
Edit: Fixed title
---
### AI Usage
While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.
Did you use AI tools to help write this code? _**< YES >**_
+33
-17
+18
-11
lib/JpegToBmpConverter/JpegToBmpConverter.cpp
+18
-11
lib/JpegToBmpConverter/JpegToBmpConverter.cpp
···
236
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uint32_t scaleY_fp = 65536;
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bool needsScaling = false;
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-
if (targetWidth > 0 && targetHeight > 0 && (imageInfo.m_width > targetWidth || imageInfo.m_height > targetHeight)) {
240
-
// Calculate scale to fit within target dimensions while maintaining aspect ratio
239
+
if (targetWidth > 0 && targetHeight > 0 && (imageInfo.m_width != targetWidth || imageInfo.m_height != targetHeight)) {
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+
// Calculate scale to fit/fill target dimensions while maintaining aspect ratio
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const float scaleToFitWidth = static_cast<float>(targetWidth) / imageInfo.m_width;
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const float scaleToFitHeight = static_cast<float>(targetHeight) / imageInfo.m_height;
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// We scale to the smaller dimension, so we can potentially crop later.
···
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scaleY_fp = (static_cast<uint32_t>(imageInfo.m_height) << 16) / outHeight;
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needsScaling = true;
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-
LOG_DBG("JPG", "Pre-scaling %dx%d -> %dx%d (fit to %dx%d)", imageInfo.m_width, imageInfo.m_height, outWidth,
265
-
outHeight, targetWidth, targetHeight);
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+
LOG_DBG("JPG", "Scaling %dx%d -> %dx%d (target %dx%d)", imageInfo.m_width, imageInfo.m_height, outWidth, outHeight,
265
+
targetWidth, targetHeight);
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}
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// Write BMP header with output dimensions
···
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rowCount[outX] += count;
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}
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-
// Check if we've crossed into the next output row
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+
// Check if we've crossed into the next output row(s)
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// Current source Y in fixed point: y << 16
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const uint32_t srcY_fp = static_cast<uint32_t>(y + 1) << 16;
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473
-
// Output row when source Y crosses the boundary
474
-
if (srcY_fp >= nextOutY_srcStart && currentOutY < outHeight) {
473
+
// Output all rows whose boundaries we've crossed (handles both up and downscaling)
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+
// For upscaling, one source row may produce multiple output rows
475
+
while (srcY_fp >= nextOutY_srcStart && currentOutY < outHeight) {
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memset(rowBuffer, 0, bytesPerRow);
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if (USE_8BIT_OUTPUT && !oneBit) {
···
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bmpOut.write(rowBuffer, bytesPerRow);
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currentOutY++;
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-
// Reset accumulators for next output row
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-
memset(rowAccum, 0, outWidth * sizeof(uint32_t));
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-
memset(rowCount, 0, outWidth * sizeof(uint16_t));
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-
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// Update boundary for next output row
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nextOutY_srcStart = static_cast<uint32_t>(currentOutY + 1) * scaleY_fp;
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+
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+
// For upscaling: don't reset accumulators if next output row uses same source data
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+
// Only reset when we'll move to a new source row
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+
if (srcY_fp >= nextOutY_srcStart) {
526
+
// More output rows to emit from same source - keep accumulator data
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+
continue;
528
+
}
529
+
// Moving to next source row - reset accumulators
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+
memset(rowAccum, 0, outWidth * sizeof(uint32_t));
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+
memset(rowCount, 0, outWidth * sizeof(uint16_t));
525
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}
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}
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}
+15
-6
lib/PngToBmpConverter/PngToBmpConverter.cpp
+15
-6
lib/PngToBmpConverter/PngToBmpConverter.cpp
···
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bool needsScaling = false;
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if (targetWidth > 0 && targetHeight > 0 &&
606
-
(static_cast<int>(width) > targetWidth || static_cast<int>(height) > targetHeight)) {
606
+
(static_cast<int>(width) != targetWidth || static_cast<int>(height) != targetHeight)) {
607
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const float scaleToFitWidth = static_cast<float>(targetWidth) / width;
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const float scaleToFitHeight = static_cast<float>(targetHeight) / height;
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float scale = 1.0;
···
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622
scaleY_fp = (static_cast<uint32_t>(height) << 16) / outHeight;
623
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needsScaling = true;
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-
LOG_DBG("PNG", "Pre-scaling %ux%u -> %dx%d (fit to %dx%d)", width, height, outWidth, outHeight, targetWidth,
625
+
LOG_DBG("PNG", "Scaling %ux%u -> %dx%d (target %dx%d)", width, height, outWidth, outHeight, targetWidth,
626
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targetHeight);
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}
628
628
···
767
767
rowCount[outX] += count;
768
768
}
769
769
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-
// Check if we've crossed into the next output row
770
+
// Check if we've crossed into the next output row(s)
771
771
const uint32_t srcY_fp = static_cast<uint32_t>(y + 1) << 16;
772
772
773
-
if (srcY_fp >= nextOutY_srcStart && currentOutY < outHeight) {
773
+
// Output all rows whose boundaries we've crossed (handles both up and downscaling)
774
+
// For upscaling, one source row may produce multiple output rows
775
+
while (srcY_fp >= nextOutY_srcStart && currentOutY < outHeight) {
774
776
memset(rowBuffer, 0, bytesPerRow);
775
777
776
778
if (USE_8BIT_OUTPUT && !oneBit) {
···
812
814
bmpOut.write(rowBuffer, bytesPerRow);
813
815
currentOutY++;
814
816
817
+
nextOutY_srcStart = static_cast<uint32_t>(currentOutY + 1) * scaleY_fp;
818
+
819
+
// For upscaling: don't reset accumulators if next output row uses same source data
820
+
// Only reset when we'll move to a new source row
821
+
if (srcY_fp >= nextOutY_srcStart) {
822
+
// More output rows to emit from same source - keep accumulator data
823
+
continue;
824
+
}
825
+
// Moving to next source row - reset accumulators
815
826
memset(rowAccum, 0, outWidth * sizeof(uint32_t));
816
827
memset(rowCount, 0, outWidth * sizeof(uint16_t));
817
-
818
-
nextOutY_srcStart = static_cast<uint32_t>(currentOutY + 1) * scaleY_fp;
819
828
}
820
829
}
821
830