Add functions for managing image to image list index mapping and caching

1 files changed, 91 insertions, 0 deletions

diff --git a/imagelist.go b/imagelist.go
index 4ad0612d..c8ec6cf7 100644
--- a/imagelist.go
+++ b/imagelist.go
@@ -4,6 +4,11 @@
 
 package walk
 
+import (
+	"syscall"
+	"unsafe"
+)
+
 import . "github.com/lxn/go-winapi"
 
 type ImageList struct {
@@ -69,3 +74,89 @@ func (il *ImageList) Dispose() {
 func (il *ImageList) MaskColor() Color {
 	return il.maskColor
 }
+
+func imageListForImage(image interface{}) (hIml HIMAGELIST, isSysIml bool, err error) {
+	if filePath, ok := image.(string); ok {
+		_, hIml = iconIndexAndHImlForFilePath(filePath)
+		isSysIml = hIml != 0
+	} else {
+		w, h := GetSystemMetrics(SM_CXSMICON), GetSystemMetrics(SM_CYSMICON)
+
+		hIml = ImageList_Create(w, h, ILC_MASK|ILC_COLOR24, 8, 8)
+		if hIml == 0 {
+			return 0, false, newError("ImageList_Create failed")
+		}
+	}
+
+	return
+}
+
+func iconIndexAndHImlForFilePath(filePath string) (int32, HIMAGELIST) {
+	var shfi SHFILEINFO
+
+	if hIml := HIMAGELIST(SHGetFileInfo(
+		syscall.StringToUTF16Ptr(filePath),
+		0,
+		&shfi,
+		uint32(unsafe.Sizeof(shfi)),
+		SHGFI_SYSICONINDEX|SHGFI_SMALLICON)); hIml != 0 {
+
+		return shfi.IIcon, hIml
+	}
+
+	return -1, 0
+}
+
+func imageIndexMaybeAdd(image interface{}, hIml HIMAGELIST, isSysIml bool, imageUintptr2Index map[uintptr]int32, filePath2IconIndex map[string]int32) int32 {
+	if !isSysIml {
+		return imageIndexAddIfNotExists(image, hIml, imageUintptr2Index)
+	} else if filePath, ok := image.(string); ok {
+		if iIcon, ok := filePath2IconIndex[filePath]; ok {
+			return iIcon
+		}
+
+		if iIcon, _ := iconIndexAndHImlForFilePath(filePath); iIcon != -1 {
+			filePath2IconIndex[filePath] = iIcon
+			return iIcon
+		}
+	}
+
+	return -1
+}
+
+func imageIndexAddIfNotExists(image interface{}, hIml HIMAGELIST, imageUintptr2Index map[uintptr]int32) int32 {
+	imageIndex := int32(-1)
+
+	if image != nil {
+		var ptr uintptr
+		switch img := image.(type) {
+		case *Bitmap:
+			ptr = uintptr(unsafe.Pointer(img))
+
+		case *Icon:
+			ptr = uintptr(unsafe.Pointer(img))
+		}
+
+		if ptr == 0 {
+			return -1
+		}
+
+		if imageIndex, ok := imageUintptr2Index[ptr]; ok {
+			return imageIndex
+		}
+
+		switch img := image.(type) {
+		case *Bitmap:
+			imageIndex = ImageList_AddMasked(hIml, img.hBmp, 0)
+
+		case *Icon:
+			imageIndex = ImageList_ReplaceIcon(hIml, -1, img.hIcon)
+		}
+
+		if imageIndex > -1 {
+			imageUintptr2Index[ptr] = imageIndex
+		}
+	}
+
+	return imageIndex
+}