[Scummvm-git-logs] scummvm master -> 3bd0dbe619043bda462c71134a031f6364aa9483

[criezy]

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pushed to the 'scummvm' repo located at https://github.com/scummvm/scummvm .

Summary:
3bd0dbe619 AGS: Improve pixel format selection


Commit: 3bd0dbe619043bda462c71134a031f6364aa9483
    https://github.com/scummvm/scummvm/commit/3bd0dbe619043bda462c71134a031f6364aa9483
Author: Thierry Crozat (criezy at scummvm.org)
Date: 2023-02-09T23:31:39Z

Commit Message:
AGS: Improve pixel format selection

The engine is capable of rendering to any 16 bit or 32 bit format,
but the format conversion has a cost. This commit assumes that any
conversion that the backend may need to do would be at least as
efficient as the conversion that would be done in the engine, so
we select the best format for the engine that is supported by the
backend. There are three categories of formats:
1. The one used internally by the engine. When also used for the
backend we can do direct rendering.
2. For 32 bit games, two additional formats for which there is
an optimized color conversion.
3. Any other 16 bit or 32 bit pixel format, for which we have
generic color conversion.

Profiling with two games shows the following improvments:
 - If we can use the internal engine format, we gain between 3%
   and 5% compared to the next best formats, and between 11% and
   14% with other formats.
 - Otherwise if we can use the next best formats we still gain
   between 6% and 11% over other formats.

Changed paths:
    engines/ags/ags.cpp


diff --git a/engines/ags/ags.cpp b/engines/ags/ags.cpp
index eb5b2125437..73d89fff2bd 100644
--- a/engines/ags/ags.cpp
+++ b/engines/ags/ags.cpp
@@ -212,14 +212,38 @@ SaveStateList AGSEngine::listSaves() const {
 }
 
 bool AGSEngine::getPixelFormat(int depth, Graphics::PixelFormat &format) const {
-	Common::List<Graphics::PixelFormat> supportedFormatsList = g_system->getSupportedFormats();
-
 	if (depth == 8) {
 		format = Graphics::PixelFormat::createFormatCLUT8();
 		return true;
 	}
 
-	// Prefer format with the requested color depth
+	Common::List<Graphics::PixelFormat> supportedFormatsList = g_system->getSupportedFormats();
+
+	// Internally the engine uses the following format (see create_bitmap_ex())
+	//  16 bit: RGB565   / Graphics::PixelFormat(2, 5, 6, 5, 0, 11, 5, 0, 0)
+	//  32 bit: ARGB8888 / Graphics::PixelFormat(4, 8, 8, 8, 8, 16, 8, 0, 24)
+	// If supported by the backend, use it so that we can do direct rendering.
+	Graphics::PixelFormat engine_format = depth == 16 ? Graphics::PixelFormat(2, 5, 6, 5, 0, 11, 5, 0, 0) : Graphics::PixelFormat(4, 8, 8, 8, 8, 16, 8, 0, 24);
+	if (Common::find(supportedFormatsList.begin(), supportedFormatsList.end(), engine_format) != supportedFormatsList.end()) {
+		format = engine_format;
+		return true;
+	}
+
+	// For 32 bit color depth, the next best formats for which there is some optimization in the
+	// engine are RGBA8888 or ABGR8888 (see ScummVMRendererGraphicsDriver::Present()).
+	if (depth == 32) {
+		Graphics::PixelFormat preferred_format1 = Graphics::PixelFormat(4, 8, 8, 8, 8, 24, 16, 8, 0);
+		Graphics::PixelFormat preferred_format2 = Graphics::PixelFormat(4, 8, 8, 8, 8, 0, 8, 16, 24);
+		for (Common::List<Graphics::PixelFormat>::iterator it =
+				supportedFormatsList.begin(); it != supportedFormatsList.end(); ++it) {
+			if (*it == preferred_format1 || *it == preferred_format2) {
+				format = *it;
+				return true;
+			}
+		}
+	}
+
+	// Otherwise prefer another format with the same color depth
 	for (Common::List<Graphics::PixelFormat>::iterator it =
 			supportedFormatsList.begin(); it != supportedFormatsList.end(); ++it) {
 		if (it->bpp() == depth) {