Improve Program icons scaling for win32 #62

This commit implements scaling of program icons by retrieving it from
SHDefExtractIcon, which also provides the system default icons for the
file type followed by a fallback if the pszFile for the icon is not
valid. The fallback uses the extension to retrieve the icon using
SHGetFileInfo in small and large size and scales it accordingly with the
required zoom level.

contributes to
#62 and
#127

Author: amartya4256

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

@@ -7498,6 +7498,28 @@ JNIEXPORT jint JNICALL OS_NATIVE(SHDRAGIMAGE_1sizeof)
 }
 #endif
 
+#ifndef NO_SHDefExtractIcon
+JNIEXPORT jint JNICALL OS_NATIVE(SHDefExtractIcon)
+	(JNIEnv *env, jclass that, jcharArray arg0, jint arg1, jint arg2, jlongArray arg3, jlongArray arg4, jint arg5)
+{
+	jchar *lparg0=NULL;
+	jlong *lparg3=NULL;
+	jlong *lparg4=NULL;
+	jint rc = 0;
+	OS_NATIVE_ENTER(env, that, SHDefExtractIcon_FUNC);
+	if (arg0) if ((lparg0 = (*env)->GetCharArrayElements(env, arg0, NULL)) == NULL) goto fail;
+	if (arg3) if ((lparg3 = (*env)->GetLongArrayElements(env, arg3, NULL)) == NULL) goto fail;
+	if (arg4) if ((lparg4 = (*env)->GetLongArrayElements(env, arg4, NULL)) == NULL) goto fail;
+	rc = (jint)SHDefExtractIcon((LPWSTR)lparg0, arg1, arg2, (HICON FAR *)lparg3, (HICON FAR *)lparg4, arg5);
+fail:
+	if (arg4 && lparg4) (*env)->ReleaseLongArrayElements(env, arg4, lparg4, 0);
+	if (arg3 && lparg3) (*env)->ReleaseLongArrayElements(env, arg3, lparg3, 0);
+	if (arg0 && lparg0) (*env)->ReleaseCharArrayElements(env, arg0, lparg0, 0);
+	OS_NATIVE_EXIT(env, that, SHDefExtractIcon_FUNC);
+	return rc;
+}
+#endif
+
 #ifndef NO_SHELLEXECUTEINFO_1sizeof
 JNIEXPORT jint JNICALL OS_NATIVE(SHELLEXECUTEINFO_1sizeof)
 	(JNIEnv *env, jclass that)

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

@@ -567,6 +567,7 @@ typedef enum {
 	SCROLLBARINFO_1sizeof_FUNC,
 	SCROLLINFO_1sizeof_FUNC,
 	SHDRAGIMAGE_1sizeof_FUNC,
+	SHDefExtractIcon_FUNC,
 	SHELLEXECUTEINFO_1sizeof_FUNC,
 	SHFILEINFO_1sizeof_FUNC,
 	SHGetFileInfo_FUNC,

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

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2022 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0

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

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2021 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0

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

@@ -4445,6 +4445,16 @@ public static int HRESULT_FROM_WIN32(int x) {
  * @param lpXform cast=(XFORM *),flags=no_out
  */
 public static final native boolean SetWorldTransform(long hdc, float[] lpXform);
+/**
+ * @param lpszFile cast=(LPWSTR)
+ * @param phiconLarge cast=(HICON FAR *)
+ * @param phiconSmall cast=(HICON FAR *)
+ */
+public static final native int SHDefExtractIcon (char [] lpszFile, int iIndex, int uFlags, long [] phiconLarge, long [] phiconSmall, int nIconSize);
+public static final int SHDefExtractIcon (TCHAR lpszFile, int iIndex, int uFlags, long [] phiconLarge, long [] phiconSmall, int nIconSize) {
+	char [] lpszFile1 = lpszFile == null ? null : lpszFile.chars;
+	return SHDefExtractIcon (lpszFile1, iIndex, uFlags, phiconLarge, phiconSmall, nIconSize);
+}
 /** @param pszPath cast=(LPCWSTR),flags=no_out */
 public static final native long SHGetFileInfo (char [] pszPath, int dwFileAttributes, SHFILEINFO psfi, int cbFileInfo, int uFlags);
 public static final native boolean ShellExecuteEx (SHELLEXECUTEINFO lpExecInfo);

bundles/org.eclipse.swt/Eclipse SWT Program/win32/org/eclipse/swt/program/Program.java

@@ -379,28 +379,6 @@ public ImageData getImageData () {
  * @since 3.125
  */
 public ImageData getImageData (int zoom) {
-	// OS.SHGetFileInfo is System DPI-aware, hence it retrieves the icon with zoom
-	// of primary monitor at the application startup
-	int initialNativeZoom = getPrimaryMonitorZoomAtStartup();
-	if (extension != null) {
-		SHFILEINFO shfi = new SHFILEINFO ();
-		int flags = OS.SHGFI_ICON | OS.SHGFI_USEFILEATTRIBUTES;
-		boolean useLargeIcon = 100 * zoom /  initialNativeZoom >= 200;
-		if(useLargeIcon) {
-			flags |= OS.SHGFI_LARGEICON;
-			initialNativeZoom *= 2;
-		} else {
-			flags |= OS.SHGFI_SMALLICON;
-		}
-		TCHAR pszPath = new TCHAR (0, extension, true);
-		OS.SHGetFileInfo (pszPath.chars, OS.FILE_ATTRIBUTE_NORMAL, shfi, SHFILEINFO.sizeof, flags);
-		if (shfi.hIcon != 0) {
-			Image image = Image.win32_new (null, SWT.ICON, shfi.hIcon, initialNativeZoom);
-			ImageData imageData = image.getImageData (zoom);
-			image.dispose ();
-			return imageData;
-		}
-	}
 	int nIconIndex = 0;
 	String fileName = iconName;
 	int index = iconName.indexOf (',');
@@ -418,15 +396,42 @@ public ImageData getImageData (int zoom) {
 		}
 	}
 	TCHAR lpszFile = new TCHAR (0, fileName, true);
-	long [] phiconSmall = new long[1], phiconLarge = null;
-	OS.ExtractIconEx (lpszFile, nIconIndex, phiconLarge, phiconSmall, 1);
-	if (phiconSmall [0] == 0) return null;
-	Image image = Image.win32_new (null, SWT.ICON, phiconSmall [0], initialNativeZoom);
+	long [] hIcon = new long[1];
+	int size = OS.GetSystemMetricsForDpi(OS.SM_CXSMICON, DPIUtil.mapZoomToDPI(zoom));
+	OS.SHDefExtractIcon (lpszFile, nIconIndex, 0, hIcon, null, size);
+	if (hIcon [0] == 0) {
+		return getImageDataUsingExtension(zoom);
+	}
+	Image image = Image.win32_new (null, SWT.ICON, hIcon [0], zoom);
 	ImageData imageData = image.getImageData (zoom);
 	image.dispose ();
 	return imageData;
 }
 
+private ImageData getImageDataUsingExtension(int zoom) {
+	if (extension != null) {
+		int initialNativeZoom = getPrimaryMonitorZoomAtStartup();
+		SHFILEINFO shfi = new SHFILEINFO ();
+		int flags = OS.SHGFI_ICON | OS.SHGFI_USEFILEATTRIBUTES;
+		boolean useLargeIcon = 100 * zoom /  initialNativeZoom >= 200;
+		if(useLargeIcon) {
+			flags |= OS.SHGFI_LARGEICON;
+			initialNativeZoom *= 2;
+		} else {
+			flags |= OS.SHGFI_SMALLICON;
+		}
+		TCHAR pszPath = new TCHAR (0, extension, true);
+		OS.SHGetFileInfo (pszPath.chars, OS.FILE_ATTRIBUTE_NORMAL, shfi, SHFILEINFO.sizeof, flags);
+		if (shfi.hIcon != 0) {
+			Image image = Image.win32_new (null, SWT.ICON, shfi.hIcon, initialNativeZoom);
+			ImageData imageData = image.getImageData (zoom);
+			image.dispose ();
+			return imageData;
+		}
+	}
+	return null;
+}
+
 private int getPrimaryMonitorZoomAtStartup() {
 	long hDC = OS.GetDC(0);
 	int dpi = OS.GetDeviceCaps(hDC, OS.LOGPIXELSX);