Removal for OS.LOGPIXELS* usage where possible #62

This commit removes the usage of OS.LOGPIXELS* in a few places in the code wherever these values can be obtained using other means as the OS.LOGPIXELS provides the dpi values of the primary monitor at the app-startup time. It's usage have been either removed completely (wherever possible) or have been replaced by DPI-Aware OS.GetDpiForMonitor calls.

contributes to #62 and #127

Author: amartya4256

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/internal/ScalingSWTFontRegistry.java

@@ -77,7 +77,7 @@ private void addScaledFont(int targetZoom, Font scaledFont) {
 
 	@Override
 	public Font getSystemFont(int zoom) {
-		ScaledFontContainer container = getOrCreateBaseSystemFontContainer(device);
+		ScaledFontContainer container = getOrCreateBaseSystemFontContainer(device, zoom);
 
 		Font systemFont = container.getScaledFont(zoom);
 		if (systemFont != null) {
@@ -89,16 +89,12 @@ public Font getSystemFont(int zoom) {
 		return systemFont;
 	}
 
-	private ScaledFontContainer getOrCreateBaseSystemFontContainer(Device device) {
+	private ScaledFontContainer getOrCreateBaseSystemFontContainer(Device device, int zoom) {
 		ScaledFontContainer systemFontContainer = fontKeyMap.get(KEY_SYSTEM_FONTS);
 		if (systemFontContainer == null) {
-			long hDC = device.internal_new_GC (null);
-			int dpiX = OS.GetDeviceCaps (hDC, OS.LOGPIXELSX);
-			device.internal_dispose_GC (hDC, null);
-			int primaryZoom = DPIUtil.mapDPIToZoom(dpiX);
-			long systemFontHandle = createSystemFont(primaryZoom);
-			Font systemFont = Font.win32_new(device, systemFontHandle, primaryZoom);
-			systemFontContainer = new ScaledFontContainer(systemFont, primaryZoom);
+			long systemFontHandle = createSystemFont(zoom);
+			Font systemFont = Font.win32_new(device, systemFontHandle, zoom);
+			systemFontContainer = new ScaledFontContainer(systemFont, zoom);
 			fontHandleMap.put(systemFont.handle, systemFontContainer);
 			fontKeyMap.put(KEY_SYSTEM_FONTS, systemFontContainer);
 		}

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/FontDialog.java

@@ -195,14 +195,15 @@ public FontData open () {
 	if (effectsVisible) {
 		lpcf.Flags |= OS.CF_EFFECTS;
 	}
+	int [] dpiX = new int[1];
+	int [] dpiY = new int[1];
+	OS.GetDpiForMonitor(getParent().getMonitor().handle, OS.MDT_EFFECTIVE_DPI, dpiX, dpiY);
 
 	long lpLogFont = OS.HeapAlloc (hHeap, OS.HEAP_ZERO_MEMORY, LOGFONT.sizeof);
 	if (fontData != null && fontData.data != null) {
 		LOGFONT logFont = fontData.data;
 		int lfHeight = logFont.lfHeight;
-		long hDC = OS.GetDC (0);
-		int pixels = -(int)(0.5f + (fontData.height * OS.GetDeviceCaps(hDC, OS.LOGPIXELSY) / 72));
-		OS.ReleaseDC (0, hDC);
+		int pixels = -(int)(0.5f + (fontData.height * dpiY[0] / 72));
 		logFont.lfHeight = pixels;
 		lpcf.Flags |= OS.CF_INITTOLOGFONTSTRUCT;
 		OS.MoveMemory (lpLogFont, logFont, LOGFONT.sizeof);
@@ -257,7 +258,7 @@ public FontData open () {
 			 * proper device.
 			 */
 			long hDC = OS.GetDC(0);
-			int logPixelsY = OS.GetDeviceCaps(hDC, OS.LOGPIXELSY);
+			int logPixelsY = dpiY[0];
 			int pixels = 0;
 			if (logFont.lfHeight > 0) {
 				/*