fix(ui): Make RenderBuffer respect DPI scaling on MacOS (endless-sky#…

…10350)

source/GameWindow.cpp

@@ -34,6 +34,8 @@ namespace {
 	SDL_GLContext context = nullptr;
 	int width = 0;
 	int height = 0;
+	int drawWidth = 0;
+	int drawHeight = 0;
 	bool supportsAdaptiveVSync = false;
 
 	// Logs SDL errors and returns true if found
@@ -330,7 +332,6 @@ void GameWindow::AdjustViewport()
 
 	// Find out the drawable dimensions. If this is a high- DPI display, this
 	// may be larger than the window.
-	int drawWidth, drawHeight;
 	SDL_GL_GetDrawableSize(mainWindow, &drawWidth, &drawHeight);
 	Screen::SetHighDPI(drawWidth > windowWidth || drawHeight > windowHeight);
 
@@ -398,6 +399,20 @@ int GameWindow::Height()
 
 
 
+int GameWindow::DrawWidth()
+{
+	return drawWidth;
+}
+
+
+
+int GameWindow::DrawHeight()
+{
+	return drawHeight;
+}
+
+
+
 bool GameWindow::IsMaximized()
 {
 	return (SDL_GetWindowFlags(mainWindow) & SDL_WINDOW_MAXIMIZED);

source/GameWindow.h

@@ -42,6 +42,10 @@ class GameWindow {
 	static int Width();
 	static int Height();
 
+	// Last known drawable width & height.
+	static int DrawWidth();
+	static int DrawHeight();
+
 	static bool IsMaximized();
 	static bool IsFullscreen();
 	static void ToggleFullscreen();

source/RenderBuffer.cpp

@@ -15,6 +15,7 @@ this program. If not, see <https://www.gnu.org/licenses/>.
 
 #include "RenderBuffer.h"
 
+#include "GameWindow.h"
 #include "Logger.h"
 #include "Screen.h"
 #include "Shader.h"
@@ -165,8 +166,10 @@ RenderBuffer::RenderBuffer(const Point &dimensions)
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 
+	multiplier = Point(GameWindow::DrawWidth() / Screen::RawWidth(), GameWindow::DrawHeight() / Screen::RawHeight());
+
 	// Attach a blank image to the texture.
-	const Point scaledSize = size * Screen::Zoom() / 100.0;
+	const Point scaledSize = size * multiplier * Screen::Zoom() / 100.0;
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, scaledSize.X(), scaledSize.Y(), 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
 
 	// Attach the texture to the frame buffer.
@@ -209,7 +212,7 @@ RenderBuffer::RenderTargetGuard RenderBuffer::SetTarget()
 	glGetIntegerv(GL_VIEWPORT, lastViewport);
 	glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
 
-	const Point scaledSize = size * Screen::Zoom() / 100.0;
+	const Point scaledSize = size * multiplier * Screen::Zoom() / 100.0;
 	glViewport(0, 0, scaledSize.X(), scaledSize.Y());
 
 	static const float CLEAR[] = {0, 0, 0, 0};

source/RenderBuffer.h

@@ -87,4 +87,6 @@ class RenderBuffer
 	int lastViewport[4] = {};
 
 	float fadePadding[4] = {};
+
+	Point multiplier;
 };