add icons to taskbar control buttons

backend/windows/taskbar_buttons.go

@@ -1,29 +1,131 @@
-//go:build windows
-
-package windows
-
-/*
-#cgo LDFLAGS: -lole32
-#include "taskbar_buttons.h"
-
-extern void goButtonClicked(int);
-*/
-import "C"
-import (
-	"unsafe"
-)
-
-var gTaskbarButtonCallback func(TaskbarButton)
-
-func InitializeTaskbarButtons(hwnd uintptr, callback func(TaskbarButton)) error {
-	gTaskbarButtonCallback = callback
-	C.initialize_taskbar_buttons(unsafe.Pointer(hwnd), C.ThumbnailCallback(C.goButtonClicked))
-	return nil
-}
-
-//export goButtonClicked
-func goButtonClicked(buttonID C.int) {
-	if gTaskbarButtonCallback != nil {
-		gTaskbarButtonCallback(TaskbarButton(buttonID))
-	}
-}
+//go:build windows
+
+package windows
+
+/*
+#cgo LDFLAGS: -lole32
+#include "taskbar_buttons.h"
+
+extern void goButtonClicked(int);
+*/
+import "C"
+import (
+	"errors"
+	"image"
+	"unsafe"
+)
+
+var gTaskbarButtonCallback func(TaskbarButton)
+
+// InitializeTaskbarIcons supplies the image icons that will be used for the taskbar buttons.
+// They must all have the same pixel dimensions.
+// This should be called before InitializeTaskbarButtons or the buttons will not have icons.
+func InitializeTaskbarIcons(prev, next, play, pause image.Image) error {
+	pB := imageToBGRA(prev)
+	nB := imageToBGRA(next)
+	plB := imageToBGRA(play)
+	paB := imageToBGRA(pause)
+	bnds := prev.Bounds()
+
+	C.initialize_taskbar_icons(unsafe.Pointer(&pB[0]), unsafe.Pointer(&nB[0]), unsafe.Pointer(&plB[0]), unsafe.Pointer(&paB[0]), C.int(bnds.Dx()), C.int(bnds.Dy()))
+	return nil
+}
+
+func InitializeTaskbarButtons(hwnd uintptr, callback func(TaskbarButton)) error {
+	gTaskbarButtonCallback = callback
+	C.initialize_taskbar_buttons(unsafe.Pointer(hwnd), C.ThumbnailCallback(C.goButtonClicked))
+	return nil
+}
+
+func SetTaskbarButtonIsPlaying(isPlaying bool) error {
+	i := C.int(0)
+	if isPlaying {
+		i = C.int(1)
+	}
+	if ret := int(C.set_is_playing(i)); ret == 0 {
+		return nil
+	}
+	return errors.New("failed to set taskbar button is playing state")
+}
+
+//export goButtonClicked
+func goButtonClicked(buttonID C.int) {
+	if gTaskbarButtonCallback != nil {
+		gTaskbarButtonCallback(TaskbarButton(buttonID))
+	}
+}
+
+// imageToBGRA converts an image.Image to a BGRA byte slice.
+// For *image.RGBA, it un-premultiplies the colors to straight alpha.
+func imageToBGRA(img image.Image) []byte {
+	bounds := img.Bounds()
+	w, h := bounds.Dx(), bounds.Dy()
+	bgra := make([]byte, w*h*4)
+
+	i := 0
+	switch src := img.(type) {
+	case *image.NRGBA:
+		// Straight alpha, just swap channels
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			off := src.PixOffset(bounds.Min.X, y)
+			for x := 0; x < w; x++ {
+				r := src.Pix[off+0]
+				g := src.Pix[off+1]
+				b := src.Pix[off+2]
+				a := src.Pix[off+3]
+				bgra[i+0] = b
+				bgra[i+1] = g
+				bgra[i+2] = r
+				bgra[i+3] = a
+				off += 4
+				i += 4
+			}
+		}
+
+	case *image.RGBA:
+		// Premultiplied alpha, un-premultiply to straight alpha
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			off := src.PixOffset(bounds.Min.X, y)
+			for x := 0; x < w; x++ {
+				r := src.Pix[off+0]
+				g := src.Pix[off+1]
+				b := src.Pix[off+2]
+				a := src.Pix[off+3]
+
+				if a != 0 {
+					// Convert from premultiplied to straight alpha
+					r = uint8((uint16(r) * 0xFF) / uint16(a))
+					g = uint8((uint16(g) * 0xFF) / uint16(a))
+					b = uint8((uint16(b) * 0xFF) / uint16(a))
+				}
+
+				bgra[i+0] = b
+				bgra[i+1] = g
+				bgra[i+2] = r
+				bgra[i+3] = a
+				off += 4
+				i += 4
+			}
+		}
+
+	default:
+		// Fallback: handle any other image.Image type via At()
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			for x := bounds.Min.X; x < bounds.Max.X; x++ {
+				r16, g16, b16, a16 := img.At(x, y).RGBA()
+				// Convert from 16-bit [0, 65535] to 8-bit [0, 255]
+				r := uint8(r16 >> 8)
+				g := uint8(g16 >> 8)
+				b := uint8(b16 >> 8)
+				a := uint8(a16 >> 8)
+				bgra[i+0] = b
+				bgra[i+1] = g
+				bgra[i+2] = r
+				bgra[i+3] = a
+				i += 4
+			}
+		}
+	}
+
+	return bgra
+}