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// Copyright 2010 The Walk Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build windows
package walk
import (
"github.com/lxn/win"
)
const customWidgetWindowClass = `\o/ Walk_CustomWidget_Class \o/`
func init() {
MustRegisterWindowClass(customWidgetWindowClass)
}
type PaintFunc func(canvas *Canvas, updateBounds Rectangle) error
type PaintMode int
const (
PaintNormal PaintMode = iota // erase background before PaintFunc
PaintNoErase // PaintFunc clears background, single buffered
PaintBuffered // PaintFunc clears background, double buffered
)
type CustomWidget struct {
WidgetBase
paint PaintFunc
invalidatesOnResize bool
paintMode PaintMode
}
func NewCustomWidget(parent Container, style uint, paint PaintFunc) (*CustomWidget, error) {
cw := &CustomWidget{paint: paint}
if err := InitWidget(
cw,
parent,
customWidgetWindowClass,
win.WS_VISIBLE|uint32(style),
0); err != nil {
return nil, err
}
return cw, nil
}
func (*CustomWidget) LayoutFlags() LayoutFlags {
return ShrinkableHorz | ShrinkableVert | GrowableHorz | GrowableVert | GreedyHorz | GreedyVert
}
func (cw *CustomWidget) SizeHint() Size {
return Size{100, 100}
}
// deprecated, use PaintMode
func (cw *CustomWidget) ClearsBackground() bool {
return cw.paintMode != PaintNormal
}
// deprecated, use SetPaintMode
func (cw *CustomWidget) SetClearsBackground(value bool) {
if value != cw.ClearsBackground() {
if value {
cw.paintMode = PaintNormal
} else {
cw.paintMode = PaintNoErase
}
}
}
func (cw *CustomWidget) InvalidatesOnResize() bool {
return cw.invalidatesOnResize
}
func (cw *CustomWidget) SetInvalidatesOnResize(value bool) {
cw.invalidatesOnResize = value
}
func (cw *CustomWidget) PaintMode() PaintMode {
return cw.paintMode
}
func (cw *CustomWidget) SetPaintMode(value PaintMode) {
cw.paintMode = value
}
func (cw *CustomWidget) WndProc(hwnd win.HWND, msg uint32, wParam, lParam uintptr) uintptr {
switch msg {
case win.WM_PAINT:
if cw.paint == nil {
newError("paint func is nil")
break
}
var ps win.PAINTSTRUCT
var hdc win.HDC
if wParam == 0 {
hdc = win.BeginPaint(cw.hWnd, &ps)
} else {
hdc = win.HDC(wParam)
}
if hdc == 0 {
newError("BeginPaint failed")
break
}
defer func() {
if wParam == 0 {
win.EndPaint(cw.hWnd, &ps)
}
}()
canvas, err := newCanvasFromHDC(hdc)
if err != nil {
newError("newCanvasFromHDC failed")
break
}
defer canvas.Dispose()
r := &ps.RcPaint
bounds := Rectangle{
int(r.Left),
int(r.Top),
int(r.Right - r.Left),
int(r.Bottom - r.Top),
}
if cw.paintMode == PaintBuffered {
err = cw.bufferedPaint(canvas, bounds)
} else {
err = cw.paint(canvas, bounds)
}
if err != nil {
newError("paint failed")
break
}
return 0
case win.WM_ERASEBKGND:
if cw.paintMode != PaintNormal {
return 1
}
case win.WM_PRINTCLIENT:
win.SendMessage(hwnd, win.WM_PAINT, wParam, lParam)
case win.WM_SIZE, win.WM_SIZING:
if cw.invalidatesOnResize {
cw.Invalidate()
}
}
return cw.WidgetBase.WndProc(hwnd, msg, wParam, lParam)
}
func (cw *CustomWidget) bufferedPaint(canvas *Canvas, updateBounds Rectangle) error {
hdc := win.CreateCompatibleDC(canvas.hdc)
if hdc == 0 {
return newError("CreateCompatibleDC failed")
}
defer win.DeleteDC(hdc)
buffered := Canvas{hdc: hdc, doNotDispose: true}
if _, err := buffered.init(); err != nil {
return err
}
w, h := int32(updateBounds.Width), int32(updateBounds.Height)
if w < 1 {
w = 1
}
if h < 1 {
h = 1
}
hbmp := win.CreateCompatibleBitmap(canvas.hdc, w, h)
if hbmp == 0 {
return lastError("CreateCompatibleBitmap failed")
}
defer win.DeleteObject(win.HGDIOBJ(hbmp))
oldbmp := win.SelectObject(buffered.hdc, win.HGDIOBJ(hbmp))
if oldbmp == 0 {
return newError("SelectObject failed")
}
defer win.SelectObject(buffered.hdc, oldbmp)
win.SetViewportOrgEx(buffered.hdc, -int32(updateBounds.X), -int32(updateBounds.Y), nil)
win.SetBrushOrgEx(buffered.hdc, -int32(updateBounds.X), -int32(updateBounds.Y), nil)
err := cw.paint(&buffered, updateBounds)
if !win.BitBlt(canvas.hdc,
int32(updateBounds.X), int32(updateBounds.Y), w, h,
buffered.hdc,
int32(updateBounds.X), int32(updateBounds.Y), win.SRCCOPY) {
return lastError("buffered BitBlt failed")
}
return err
}
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