speed optimizations: skip setting multiple times, "fastpath" if no scaling needed

This commit is contained in:
Damian Schneider
2025-11-08 12:01:40 +01:00
parent 0e043b2a1b
commit 69dfe6c8a1

View File

@@ -44,6 +44,8 @@ bool openGif(const char *filename) {
Segment* activeSeg;
uint16_t gifWidth, gifHeight;
int lastCoordinate; // last coordinate (x+y) that was set, used to reduce redundant pixel writes
uint16_t perPixelX, perPixelY; // scaling factors when upscaling
void screenClearCallback(void) {
activeSeg->fill(0);
@@ -51,26 +53,34 @@ void screenClearCallback(void) {
void updateScreenCallback(void) {}
void drawPixelCallback(int16_t x, int16_t y, uint8_t red, uint8_t green, uint8_t blue) {
if (activeSeg->height() == 1) {
// 1D strip: load pixel-by-pixel left to right, top to bottom (0/0 = top-left in gifs), scale if needed
int totalImgPix = (int)gifWidth * gifHeight;
int stripLen = activeSeg->vWidth();
if (totalImgPix - stripLen == 1) totalImgPix--; // handle off-by-one: skip last pixel instead of first
int start = ((int)y * gifWidth + (int)x) * stripLen / totalImgPix; // simple nearest-neighbor scaling
int end = (((int)y * gifWidth + (int)x+1) * stripLen + totalImgPix-1) / totalImgPix;
for (int i = start; i < end; i++) {
activeSeg->setPixelColor(i, red, green, blue);
}
} else {
// simple nearest-neighbor scaling
int outY = (int)y * activeSeg->vHeight() / gifHeight;
int outX = (int)x * activeSeg->vWidth() / gifWidth;
// set multiple pixels if upscaling
for (int i = 0; i < (activeSeg->vWidth()+(gifWidth-1)) / gifWidth; i++) {
for (int j = 0; j < (activeSeg->vHeight()+(gifHeight-1)) / gifHeight; j++) {
activeSeg->setPixelColorXY(outX + i, outY + j, red, green, blue);
}
// note: GifDecoder drawing is done top right to bottom left, line by line
// callback to draw a pixel at (x,y) without scaling: used if GIF size matches segment size (faster)
void drawPixelCallbackNoScale(int16_t x, int16_t y, uint8_t red, uint8_t green, uint8_t blue) {
activeSeg->setPixelColor(y * activeSeg->width() + x, red, green, blue);
}
void drawPixelCallback1D(int16_t x, int16_t y, uint8_t red, uint8_t green, uint8_t blue) {
// 1D strip: load pixel-by-pixel left to right, top to bottom (0/0 = top-left in gifs)
int totalImgPix = (int)gifWidth * gifHeight;
int start = ((int)y * gifWidth + (int)x) * activeSeg->vWidth() / totalImgPix; // simple nearest-neighbor scaling
if (start == lastCoordinate) return; // skip setting same coordinate again
lastCoordinate = start;
for (int i = 0; i < perPixelX; i++) {
activeSeg->setPixelColor(start + i, red, green, blue);
}
}
void drawPixelCallback2D(int16_t x, int16_t y, uint8_t red, uint8_t green, uint8_t blue) {
// simple nearest-neighbor scaling
int outY = (int)y * activeSeg->vHeight() / gifHeight;
int outX = (int)x * activeSeg->vWidth() / gifWidth;
if (outX + outY == lastCoordinate) return; // skip setting same coordinate again
lastCoordinate = outX + outY; // since input is a "scanline" this is sufficient to identify a "unique" coordinate
// set multiple pixels if upscaling
for (int i = 0; i < perPixelX; i++) {
for (int j = 0; j < perPixelY; j++) {
activeSeg->setPixelColorXY(outX + i, outY + j, red, green, blue);
}
}
}
@@ -104,9 +114,10 @@ byte renderImageToSegment(Segment &seg) {
if (file) file.close();
openGif(lastFilename);
if (!file) { gifDecodeFailed = true; return IMAGE_ERROR_FILE_MISSING; }
lastCoordinate = -1;
decoder.setScreenClearCallback(screenClearCallback);
decoder.setUpdateScreenCallback(updateScreenCallback);
decoder.setDrawPixelCallback(drawPixelCallback);
decoder.setDrawPixelCallback(drawPixelCallbackNoScale);
decoder.setFileSeekCallback(fileSeekCallback);
decoder.setFilePositionCallback(filePositionCallback);
decoder.setFileReadCallback(fileReadCallback);
@@ -116,6 +127,22 @@ byte renderImageToSegment(Segment &seg) {
DEBUG_PRINTLN(F("Starting decoding"));
if(decoder.startDecoding() < 0) { gifDecodeFailed = true; return IMAGE_ERROR_GIF_DECODE; }
DEBUG_PRINTLN(F("Decoding started"));
// after startDecoding, we can get GIF size, update static variables and callbacks if needed
decoder.getSize(&gifWidth, &gifHeight);
if (activeSeg->height() == 1) {
int totalImgPix = (int)gifWidth * gifHeight;
if (totalImgPix - activeSeg->vWidth() == 1) totalImgPix--; // handle off-by-one: skip last pixel instead of first (gifs constructed from 1D input padds last pixel if length is odd)
perPixelX = (activeSeg->vWidth() + totalImgPix-1) / totalImgPix;
if (totalImgPix != activeSeg->vWidth()) {
decoder.setDrawPixelCallback(drawPixelCallback1D); // use 1D callback with scaling
}
} else {
perPixelX = (activeSeg->vWidth() + gifWidth -1) / gifWidth;
perPixelY = (activeSeg->vHeight() + gifHeight-1) / gifHeight;
if (activeSeg->vWidth() != gifWidth || activeSeg->vHeight() != gifHeight) {
decoder.setDrawPixelCallback(drawPixelCallback2D); // use 2D callback with scaling
}
}
}
if (gifDecodeFailed) return IMAGE_ERROR_PREV;
@@ -129,8 +156,6 @@ byte renderImageToSegment(Segment &seg) {
// TODO consider handling this on FX level with a different frametime, but that would cause slow gifs to speed up during transitions
if (millis() - lastFrameDisplayTime < wait) return IMAGE_ERROR_WAITING;
decoder.getSize(&gifWidth, &gifHeight);
int result = decoder.decodeFrame(false);
if (result < 0) { gifDecodeFailed = true; return IMAGE_ERROR_FRAME_DECODE; }