add `stb_image_resize2` to replace `imageScaleNNAA` (#2971)

* add ImageResizer class

* add stb_image_resize2.h (public domain)

* add imageScaleSTB implement

* cleanup #include

gframe/image_manager.cpp

 #include "image_manager.h"
+#include "image_resizer.h"
 #include "game.h"
-#include <cmath>
 #include <thread>
-#ifdef _OPENMP
-#include <omp.h>
-#endif
 
 namespace ygo {
 
@@ -120,85 +117,8 @@ void ImageManager::ResizeTexture() {
 	if(!tBackGround_deck)
 		tBackGround_deck = tBackGround;
 }
-/**
- * Scale image using nearest neighbor anti-aliasing.
- * Function by Warr1024, from https://github.com/minetest/minetest/issues/2419, modified.
- */
-void imageScaleNNAA(irr::video::IImage* src, irr::video::IImage* dest, bool use_threading) {
-	const auto& srcDim = src->getDimension();
-	const auto& destDim = dest->getDimension();
-	if (destDim.Width == 0 || destDim.Height == 0)
-		return;
-
-	// Cache scale ratios.
-	const double rx = (double)srcDim.Width / destDim.Width;
-	const double ry = (double)srcDim.Height / destDim.Height;
-
-#pragma omp parallel if(use_threading)
-{
-	// Walk each destination image pixel.
-#pragma omp for schedule(dynamic)
-	for(irr::s32 dy = 0; dy < (irr::s32)destDim.Height; dy++) {
-		for(irr::s32 dx = 0; dx < (irr::s32)destDim.Width; dx++) {
-			// Calculate floating-point source rectangle bounds.
-			double minsx = dx * rx;
-			double maxsx = minsx + rx;
-			double minsy = dy * ry;
-			double maxsy = minsy + ry;
-			irr::u32 sx_begin = (irr::u32)std::floor(minsx);
-			irr::u32 sx_end = (irr::u32)std::ceil(maxsx);
-			if (sx_end > srcDim.Width)
-				sx_end = srcDim.Width;
-			irr::u32 sy_begin = (irr::u32)std::floor(minsy);
-			irr::u32 sy_end = (irr::u32)std::ceil(maxsy);
-			if (sy_end > srcDim.Height)
-				sy_end = srcDim.Height;
-
-			// Total area, and integral of r, g, b values over that area,
-			// initialized to zero, to be summed up in next loops.
-			double area = 0, ra = 0, ga = 0, ba = 0, aa = 0;
-			irr::video::SColor pxl, npxl;
-
-			// Loop over the integral pixel positions described by those bounds.
-			for(irr::u32 sy = sy_begin; sy < sy_end; sy++) {
-				for(irr::u32 sx = sx_begin; sx < sx_end; sx++) {
-					// Calculate width, height, then area of dest pixel
-					// that's covered by this source pixel.
-					double pw = 1;
-					if(minsx > sx)
-						pw += sx - minsx;
-					if(maxsx < (sx + 1))
-						pw += maxsx - sx - 1;
-					double ph = 1;
-					if(minsy > sy)
-						ph += sy - minsy;
-					if(maxsy < (sy + 1))
-						ph += maxsy - sy - 1;
-					double pa = pw * ph;
-
-					// Get source pixel and add it to totals, weighted
-					// by covered area and alpha.
-					pxl = src->getPixel(sx, sy);
-					area += pa;
-					ra += pa * pxl.getRed();
-					ga += pa * pxl.getGreen();
-					ba += pa * pxl.getBlue();
-					aa += pa * pxl.getAlpha();
-				}
-			}
-			// Set the destination image pixel to the average color.
-			if(area > 0) {
-				npxl.set((irr::u32)(aa / area + 0.5),
-						 (irr::u32)(ra / area + 0.5),
-						 (irr::u32)(ga / area + 0.5),
-						 (irr::u32)(ba / area + 0.5));
-			} else {
-				npxl.set(0);
-			}
-			dest->setPixel(dx, dy, npxl);
-		}
-	}
-} // end of parallel region
+void ImageManager::resizeImage(irr::video::IImage* src, irr::video::IImage* dest, bool use_threading) {
+	imageResizer.resize(src, dest, use_threading);
 }
 /**
  * Convert image to texture, resizing if needed.
@@ -214,7 +134,7 @@ irr::video::ITexture* ImageManager::addTexture(const char* name, irr::video::IIm
 		texture = driver->addTexture(name, srcimg);
 	} else {
 		irr::video::IImage* destimg = driver->createImage(srcimg->getColorFormat(), irr::core::dimension2d<irr::u32>(width, height));
-		imageScaleNNAA(srcimg, destimg, mainGame->gameConf.use_image_scale_multi_thread);
+		resizeImage(srcimg, destimg, mainGame->gameConf.use_image_scale_multi_thread);
 		texture = driver->addTexture(name, destimg);
 		destimg->drop();
 	}
@@ -335,7 +255,7 @@ int ImageManager::LoadThumbThread() {
 				imageManager.tThumbLoadingMutex.unlock();
 			} else {
 				irr::video::IImage *destimg = imageManager.driver->createImage(img->getColorFormat(), irr::core::dimension2d<irr::u32>(width, height));
-				imageScaleNNAA(img, destimg, mainGame->gameConf.use_image_scale_multi_thread);
+				imageManager.resizeImage(img, destimg, mainGame->gameConf.use_image_scale_multi_thread);
 				img->drop();
 				imageManager.tThumbLoadingMutex.lock();
 				if(imageManager.tThumbLoadingThreadRunning)

gframe/image_manager.h

@@ -11,6 +11,7 @@ namespace ygo {
 
 class ImageManager {
 private:
+	void resizeImage(irr::video::IImage* src, irr::video::IImage* dest, bool use_threading);
 	irr::video::ITexture* addTexture(const char* name, irr::video::IImage* srcimg, irr::s32 width, irr::s32 height);
 public:
 	bool Initial();

gframe/image_resizer.cpp

+#include "image_resizer.h"
+#include <cmath>
+#ifdef _OPENMP
+#include <omp.h>
+#endif
+
+#define STB_IMAGE_RESIZE2_IMPLEMENTATION
+#include "stb_image_resize2.h"
+
+namespace ygo {
+
+ImageResizer imageResizer;
+
+struct StbSamplerCache {
+	STBIR_RESIZE resize{};
+	int in_w = 0;
+	int in_h = 0;
+	int out_w = 0;
+	int out_h = 0;
+	stbir_pixel_layout layout = STBIR_BGRA;
+	bool samplers_built = false;
+
+	~StbSamplerCache() {
+		if(samplers_built) {
+			stbir_free_samplers(&resize);
+			samplers_built = false;
+		}
+	}
+
+	void reset_if_needed(int new_in_w, int new_in_h, int new_out_w, int new_out_h, stbir_pixel_layout new_layout) {
+		if(new_in_w == in_w && new_in_h == in_h && new_out_w == out_w && new_out_h == out_h && new_layout == layout)
+			return;
+		if(samplers_built) {
+			stbir_free_samplers(&resize);
+			samplers_built = false;
+		}
+		in_w = new_in_w;
+		in_h = new_in_h;
+		out_w = new_out_w;
+		out_h = new_out_h;
+		layout = new_layout;
+		resize = STBIR_RESIZE{};
+	}
+};
+
+/**
+ * Scale image using stb_image_resize2.
+ * Returns true on success, false on failure or unsupported format.
+ */
+bool ImageResizer::imageScaleSTB(irr::video::IImage* src, irr::video::IImage* dest) {
+	if(!src || !dest)
+		return false;
+
+	const auto srcDim = src->getDimension();
+	const auto destDim = dest->getDimension();
+	if(srcDim.Width == 0 || srcDim.Height == 0 || destDim.Width == 0 || destDim.Height == 0)
+		return false;
+	if(src->getColorFormat() != dest->getColorFormat())
+		return false;
+
+	stbir_pixel_layout layout = STBIR_BGRA;
+	// Fast-paths (8-bit per channel only):
+	// - ECF_A8R8G8B8: Irrlicht stores as BGRA in memory on little-endian.
+	// - ECF_R8G8B8: common for JPEGs (3 channels).
+	switch(src->getColorFormat()) {
+	case irr::video::ECF_A8R8G8B8:
+		layout = STBIR_BGRA;
+		break;
+	case irr::video::ECF_R8G8B8:
+		layout = STBIR_RGB;
+		break;
+	default:
+		return false;
+	}
+
+	void* srcPtr = src->lock();
+	if(!srcPtr)
+		return false;
+	void* destPtr = dest->lock();
+	if(!destPtr) {
+		src->unlock();
+		return false;
+	}
+
+	const int srcStride = (int)src->getPitch();
+	const int destStride = (int)dest->getPitch();
+
+	thread_local StbSamplerCache cache;
+	cache.reset_if_needed((int)srcDim.Width, (int)srcDim.Height, (int)destDim.Width, (int)destDim.Height, layout);
+
+	if(!cache.samplers_built) {
+		stbir_resize_init(&cache.resize,
+						  srcPtr, (int)srcDim.Width, (int)srcDim.Height, srcStride,
+						  destPtr, (int)destDim.Width, (int)destDim.Height, destStride,
+						  layout, STBIR_TYPE_UINT8);
+		stbir_set_edgemodes(&cache.resize, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP);
+		// Use box filters to reduce aliasing when downscaling.
+		stbir_set_filters(&cache.resize, STBIR_FILTER_BOX, STBIR_FILTER_BOX);
+		cache.samplers_built = (stbir_build_samplers(&cache.resize) != 0);
+		if(!cache.samplers_built) {
+			dest->unlock();
+			src->unlock();
+			return false;
+		}
+	} else {
+		// Reuse samplers but update buffer pointers for the current images
+		stbir_set_buffer_ptrs(&cache.resize, srcPtr, srcStride, destPtr, destStride);
+	}
+
+	const int ok = stbir_resize_extended(&cache.resize);
+	dest->unlock();
+	src->unlock();
+	return ok != 0;
+}
+
+/**
+ * Scale image using nearest neighbor anti-aliasing.
+ * Function by Warr1024, from https://github.com/minetest/minetest/issues/2419, modified.
+ */
+void ImageResizer::imageScaleNNAA(irr::video::IImage* src, irr::video::IImage* dest, bool use_threading) {
+	const auto& srcDim = src->getDimension();
+	const auto& destDim = dest->getDimension();
+	if (destDim.Width == 0 || destDim.Height == 0)
+		return;
+
+	// Cache scale ratios.
+	const double rx = (double)srcDim.Width / destDim.Width;
+	const double ry = (double)srcDim.Height / destDim.Height;
+
+#pragma omp parallel if(use_threading)
+{
+	// Walk each destination image pixel.
+#pragma omp for schedule(dynamic)
+	for(irr::s32 dy = 0; dy < (irr::s32)destDim.Height; dy++) {
+		for(irr::s32 dx = 0; dx < (irr::s32)destDim.Width; dx++) {
+			// Calculate floating-point source rectangle bounds.
+			double minsx = dx * rx;
+			double maxsx = minsx + rx;
+			double minsy = dy * ry;
+			double maxsy = minsy + ry;
+			irr::u32 sx_begin = (irr::u32)std::floor(minsx);
+			irr::u32 sx_end = (irr::u32)std::ceil(maxsx);
+			if (sx_end > srcDim.Width)
+				sx_end = srcDim.Width;
+			irr::u32 sy_begin = (irr::u32)std::floor(minsy);
+			irr::u32 sy_end = (irr::u32)std::ceil(maxsy);
+			if (sy_end > srcDim.Height)
+				sy_end = srcDim.Height;
+
+			// Total area, and integral of r, g, b values over that area,
+			// initialized to zero, to be summed up in next loops.
+			double area = 0, ra = 0, ga = 0, ba = 0, aa = 0;
+			irr::video::SColor pxl, npxl;
+
+			// Loop over the integral pixel positions described by those bounds.
+			for(irr::u32 sy = sy_begin; sy < sy_end; sy++) {
+				for(irr::u32 sx = sx_begin; sx < sx_end; sx++) {
+					// Calculate width, height, then area of dest pixel
+					// that's covered by this source pixel.
+					double pw = 1;
+					if(minsx > sx)
+						pw += sx - minsx;
+					if(maxsx < (sx + 1))
+						pw += maxsx - sx - 1;
+					double ph = 1;
+					if(minsy > sy)
+						ph += sy - minsy;
+					if(maxsy < (sy + 1))
+						ph += maxsy - sy - 1;
+					double pa = pw * ph;
+
+					// Get source pixel and add it to totals, weighted
+					// by covered area and alpha.
+					pxl = src->getPixel(sx, sy);
+					area += pa;
+					ra += pa * pxl.getRed();
+					ga += pa * pxl.getGreen();
+					ba += pa * pxl.getBlue();
+					aa += pa * pxl.getAlpha();
+				}
+			}
+			// Set the destination image pixel to the average color.
+			if(area > 0) {
+				npxl.set((irr::u32)(aa / area + 0.5),
+						 (irr::u32)(ra / area + 0.5),
+						 (irr::u32)(ga / area + 0.5),
+						 (irr::u32)(ba / area + 0.5));
+			} else {
+				npxl.set(0);
+			}
+			dest->setPixel(dx, dy, npxl);
+		}
+	}
+} // end of parallel region
+}
+
+void ImageResizer::resize(irr::video::IImage* src, irr::video::IImage* dest, bool use_threading) {
+	if(imageScaleSTB(src, dest))
+		return;
+	imageScaleNNAA(src, dest, use_threading);
+}
+
+} // namespace ygo

gframe/image_resizer.h

+#ifndef IMAGE_RESIZER_H
+#define IMAGE_RESIZER_H
+
+#include <irrlicht.h>
+
+namespace ygo {
+
+class ImageResizer {
+private:
+	bool imageScaleSTB(irr::video::IImage* src, irr::video::IImage* dest);
+	void imageScaleNNAA(irr::video::IImage* src, irr::video::IImage* dest, bool use_threading);
+public:
+	void resize(irr::video::IImage* src, irr::video::IImage* dest, bool use_threading);
+};
+
+extern ImageResizer imageResizer;
+
+} // namespace ygo
+
+#endif // IMAGE_RESIZER_H