OPENGL: Remove use of floats for aspect ratio correction. Improved fullscreen toggling default mode selection.

Floats can lead to calculation errors because, now uints are used and aspect ratio values are handled with a x 10000 scale.
When entering fullscreen, it will be looked for the fullscreen mode with the smallest metric that mantains the game screen aspect ratio.

svn-id: r51563

1 files changed, 34 insertions, 22 deletions

diff --git a/backends/graphics/openglsdl/openglsdl-graphics.cpp b/backends/graphics/openglsdl/openglsdl-graphics.cpp
index 1ac892b5b1..5b71df68af 100644
--- a/backends/graphics/openglsdl/openglsdl-graphics.cpp
+++ b/backends/graphics/openglsdl/openglsdl-graphics.cpp
@@ -199,20 +199,21 @@ bool OpenGLSdlGraphicsManager::loadGFXMode() {
 		_videoMode.hardwareWidth = _videoMode.overlayWidth;
 		_videoMode.hardwareHeight = _videoMode.overlayHeight;
 
-		float screenAspectRatio = (float)_videoMode.screenWidth / _videoMode.screenHeight;
-		float desiredAspectRatio = getAspectRatio();
+		int screenAspectRatio = _videoMode.screenWidth * 10000 / _videoMode.screenHeight;
+		int desiredAspectRatio = getAspectRatio();
 	
 		// Do not downscale dimensions, only enlarge them if needed
 		if (screenAspectRatio > desiredAspectRatio)
-			_videoMode.hardwareHeight = (int)(_videoMode.overlayWidth / desiredAspectRatio + 0.5f);
+			_videoMode.hardwareHeight = _videoMode.overlayWidth * 10000 / desiredAspectRatio;
 		else if (screenAspectRatio < desiredAspectRatio)
-			_videoMode.hardwareWidth = (int)(_videoMode.overlayHeight * desiredAspectRatio + 0.5f);
+			_videoMode.hardwareWidth = _videoMode.overlayHeight * desiredAspectRatio / 10000;
 
 		// Only adjust the overlay height if it is bigger than original one. If
 		// the width is modified it can break the overlay.
 		if (_videoMode.hardwareHeight > _videoMode.overlayHeight)
 			_videoMode.overlayHeight = _videoMode.hardwareHeight;
 	}
+	
 
 	_screenResized = false;
 
@@ -232,30 +233,40 @@ bool OpenGLSdlGraphicsManager::loadGFXMode() {
 			int bestModeIndex = 0;
 			uint bestMetric = (uint)-1;
 
+			// Best Aspect Ratio mode
+			const SDL_Rect *bestARMode = NULL;
+			int bestARModeIndex = 0;
+			uint bestARMetric = (uint)-1;
+
+			int targetAspectRatio = _videoMode.overlayWidth * 10000 / _videoMode.overlayHeight;
+
 			// Iterate over all available fullscreen modes
 			for (int i = 0; const SDL_Rect *mode = availableModes[i]; i++) {
-				// Prefer the native resolution over other modes
-				if(mode->w == _desktopWidth && mode->h == _desktopHeight) {
-					bestMode = mode;
-					bestModeIndex = i;
-					break;
-				}
-
-				if (mode->w < _videoMode.hardwareWidth)
+				if (mode->w < _videoMode.overlayWidth)
 					continue;
-				if (mode->h < _videoMode.hardwareHeight)
+				if (mode->h < _videoMode.overlayHeight)
 					continue;
 
-				uint metric = mode->w * mode->h - _videoMode.hardwareWidth * _videoMode.hardwareHeight;
-				if (metric > bestMetric)
-					continue;
-
-				bestMode = mode;
-				bestMetric = metric;
-				bestModeIndex = i;
+				uint metric = mode->w * mode->h - _videoMode.overlayWidth * _videoMode.overlayHeight;
+				if (metric < bestMetric) {
+					bestMode = mode;
+					bestMetric = metric;
+					bestModeIndex = i;
+				}
+				if (mode->w * 10000 / mode->h == targetAspectRatio) {
+					bestARMode = mode;
+					bestARModeIndex = i;
+					bestARMetric = metric;
+				}
 			}
 
-			if (bestMode) {
+			if (bestARMode) {
+				// Prefer modes that conserves the aspect ratio
+				_videoMode.hardwareWidth = bestARMode->w;
+				_videoMode.hardwareHeight = bestARMode->h;
+
+				_videoMode.activeFullscreenMode = bestARModeIndex;
+			} else if (bestMode) {
 				// If there is a suiting mode, use it
 				_videoMode.hardwareWidth = bestMode->w;
 				_videoMode.hardwareHeight = bestMode->h;
@@ -333,7 +344,8 @@ bool OpenGLSdlGraphicsManager::handleScalerHotkeys(Common::KeyCode key) {
 		char buffer[128];
 		sprintf(buffer, "Current aspect ratio mode: %s\n%d x %d -> %d x %d",
 			getAspectRatioName().c_str(),
-			_videoMode.screenWidth, _videoMode.screenHeight,
+			_videoMode.screenWidth * _videoMode.scaleFactor,
+			_videoMode.screenHeight * _videoMode.scaleFactor,
 			_hwscreen->w, _hwscreen->h
 			);
 		displayMessageOnOSD(buffer);