Improve scaling of SystemImage #62

This commit contributes to better scaling of Images obtained from
Display::getSystemImage using better windows API LoadIconWithScaleDown
for scaling. The new API also changes the old system icons to the new Windows System Icons.

Contributes to
#62 and
#127

Author: amartya4256

bundles/org.eclipse.swt/Eclipse SWT PI/win32/library/os.c

@@ -4745,6 +4745,22 @@ JNIEXPORT jint JNICALL OS_NATIVE(LoadIconMetric)
 }
 #endif
 
+#ifndef NO_LoadIconWithScaleDown
+JNIEXPORT jlong JNICALL OS_NATIVE(LoadIconWithScaleDown)
+	(JNIEnv *env, jclass that, jlong arg0, jlong arg1, jint arg2, jint arg3, jlongArray arg4)
+{
+	jlong *lparg4=NULL;
+	jlong rc = 0;
+	OS_NATIVE_ENTER(env, that, LoadIconWithScaleDown_FUNC);
+	if (arg4) if ((lparg4 = (*env)->GetLongArrayElements(env, arg4, NULL)) == NULL) goto fail;
+	rc = (jlong)LoadIconWithScaleDown((HINSTANCE)arg0, (LPWSTR)arg1, arg2, arg3, (HICON *)lparg4);
+fail:
+	if (arg4 && lparg4) (*env)->ReleaseLongArrayElements(env, arg4, lparg4, 0);
+	OS_NATIVE_EXIT(env, that, LoadIconWithScaleDown_FUNC);
+	return rc;
+}
+#endif
+
 #ifndef NO_LoadImage
 JNIEXPORT jlong JNICALL OS_NATIVE(LoadImage)
 	(JNIEnv *env, jclass that, jlong arg0, jlong arg1, jint arg2, jint arg3, jint arg4, jint arg5)

bundles/org.eclipse.swt/Eclipse SWT PI/win32/library/os_stats.h

@@ -366,6 +366,7 @@ typedef enum {
 	LoadCursor_FUNC,
 	LoadIcon_FUNC,
 	LoadIconMetric_FUNC,
+	LoadIconWithScaleDown_FUNC,
 	LoadImage_FUNC,
 	LoadKeyboardLayout_FUNC,
 	LocalFree_FUNC,

bundles/org.eclipse.swt/Eclipse SWT PI/win32/org/eclipse/swt/internal/win32/OS.java

@@ -3302,6 +3302,12 @@ public static int HRESULT_FROM_WIN32(int x) {
  * @param lpszName cast=(LPWSTR)
  */
 public static final native long LoadImage (long hinst, long lpszName, int uType, int cxDesired, int cyDesired, int fuLoad);
+/**
+ * @param hinst cast=(HINSTANCE)
+ * @param lpszName cast=(LPWSTR)
+ * @param phico cast=(HICON *)
+ */
+public static final native long LoadIconWithScaleDown (long hinst, long lpszName, int cxDesired, int cyDesired, long [] phico);
 /**
  * @param pwszKLID cast=(LPCWSTR)
  * @param Flags cast=(UINT)

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

@@ -530,6 +530,15 @@ public class Display extends Device implements Executor {
 	static int SWT_RESTORECARET;
 	static int DI_GETDRAGIMAGE;
 	static int SWT_OPENDOC;
+	private static int ICON_SIZE_AT_100 = retrieveDefaultIconSize();
+
+	private static int retrieveDefaultIconSize() {
+		if (OS.WIN32_BUILD >= OS.WIN32_BUILD_WIN10_1607) {
+			return OS.GetSystemMetricsForDpi(OS.SM_CXICON, DPIUtil.mapZoomToDPI(100));
+		} else {
+			return 32;
+		}
+	}
 
 	/* Skinning support */
 	Widget [] skinList = new Widget [GROW_SIZE];
@@ -2552,33 +2561,44 @@ Font getSystemFont (int zoom) {
  */
 public Image getSystemImage (int id) {
 	checkDevice ();
-	int primaryMonitorNativeZoom = getPrimaryMonitor().getZoom();
 	switch (id) {
 		case SWT.ICON_ERROR: {
 			if (errorImage != null) return errorImage;
-			long hIcon = OS.LoadImage (0, OS.OIC_HAND, OS.IMAGE_ICON, 0, 0, OS.LR_SHARED);
-			return errorImage = Image.win32_new (this, SWT.ICON, hIcon, primaryMonitorNativeZoom);
+			errorImage = new Image(this, getImageDataProviderForIcon(OS.OIC_HAND));
+			return errorImage;
 		}
 		case SWT.ICON_WORKING:
 		case SWT.ICON_INFORMATION: {
 			if (infoImage != null) return infoImage;
-			long hIcon = OS.LoadImage (0, OS.OIC_INFORMATION, OS.IMAGE_ICON, 0, 0, OS.LR_SHARED);
-			return infoImage = Image.win32_new (this, SWT.ICON, hIcon, primaryMonitorNativeZoom);
+			infoImage = new Image(this, getImageDataProviderForIcon(OS.OIC_INFORMATION));
+			return infoImage;
 		}
 		case SWT.ICON_QUESTION: {
 			if (questionImage != null) return questionImage;
-			long hIcon = OS.LoadImage (0, OS.OIC_QUES, OS.IMAGE_ICON, 0, 0, OS.LR_SHARED);
-			return questionImage = Image.win32_new (this, SWT.ICON, hIcon, primaryMonitorNativeZoom);
+			questionImage = new Image(this, getImageDataProviderForIcon(OS.OIC_QUES));
+			return questionImage;
 		}
 		case SWT.ICON_WARNING: {
 			if (warningIcon != null) return warningIcon;
-			long hIcon = OS.LoadImage (0, OS.OIC_BANG, OS.IMAGE_ICON, 0, 0, OS.LR_SHARED);
-			return warningIcon = Image.win32_new (this, SWT.ICON, hIcon, primaryMonitorNativeZoom);
+			warningIcon = new Image(this, getImageDataProviderForIcon(OS.OIC_BANG));
+			return warningIcon;
 		}
 	}
 	return null;
 }
 
+private ImageDataProvider getImageDataProviderForIcon(int iconName) {
+	return zoom -> {
+		int scaledIconSize = DPIUtil.scaleUp(ICON_SIZE_AT_100, zoom);
+		long [] hIcon = new long [1];
+		OS.LoadIconWithScaleDown(0, iconName, scaledIconSize, scaledIconSize, hIcon);
+		Image image = Image.win32_new (this, SWT.ICON, hIcon[0], zoom);
+		ImageData imageData = image.getImageData(zoom);
+		image.dispose();
+		return imageData;
+	};
+}
+
 /**
  * Returns the single instance of the system-provided menu for the application, or
  * <code>null</code> on platforms where no menu is provided for the application.