Delphi 画布绘制-如何改进此Alpha绘制例程?
我正在使用不透明(Alpha透明)功能在画布上绘图,如下所示:Delphi 画布绘制-如何改进此Alpha绘制例程?,delphi,delphi-xe,Delphi,Delphi Xe,我正在使用不透明(Alpha透明)功能在画布上绘图,如下所示: var Form1: TForm1; IsDrawing: Boolean; implementation {$R *.dfm} procedure DrawOpacityBrush(ACanvas: TCanvas; X, Y: Integer; AColor: TColor; ASize: Integer; Opacity: Byte); var Bmp: TBitmap; I, J: Integer;
var
Form1: TForm1;
IsDrawing: Boolean;
implementation
{$R *.dfm}
procedure DrawOpacityBrush(ACanvas: TCanvas; X, Y: Integer; AColor: TColor; ASize: Integer; Opacity: Byte);
var
Bmp: TBitmap;
I, J: Integer;
Pixels: PRGBQuad;
ColorRgb: Integer;
ColorR, ColorG, ColorB: Byte;
begin
Bmp := TBitmap.Create;
try
Bmp.PixelFormat := pf32Bit; // needed for an alpha channel
Bmp.SetSize(ASize, ASize);
with Bmp.Canvas do
begin
Brush.Color := clFuchsia; // background color to mask out
ColorRgb := ColorToRGB(Brush.Color);
FillRect(Rect(0, 0, ASize, ASize));
Pen.Color := AColor;
Pen.Style := psSolid;
Pen.Width := ASize;
MoveTo(ASize div 2, ASize div 2);
LineTo(ASize div 2, ASize div 2);
end;
ColorR := GetRValue(ColorRgb);
ColorG := GetGValue(ColorRgb);
ColorB := GetBValue(ColorRgb);
for I := 0 to Bmp.Height-1 do
begin
Pixels := PRGBQuad(Bmp.ScanLine[I]);
for J := 0 to Bmp.Width-1 do
begin
with Pixels^ do
begin
if (rgbRed = ColorR) and (rgbGreen = ColorG) and (rgbBlue = ColorB) then
rgbReserved := 0
else
rgbReserved := Opacity;
// must pre-multiply the pixel with its alpha channel before drawing
rgbRed := (rgbRed * rgbReserved) div $FF;
rgbGreen := (rgbGreen * rgbReserved) div $FF;
rgbBlue := (rgbBlue * rgbReserved) div $FF;
end;
Inc(Pixels);
end;
end;
ACanvas.Draw(X, Y, Bmp, 255);
finally
Bmp.Free;
end;
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
case Button of
mbLeft:
begin
IsDrawing := True;
DrawOpacityBrush(Form1.Canvas, X, Y, clRed, 50, 85);
end;
end;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
if (GetAsyncKeyState(VK_LBUTTON) <> 0) and
(IsDrawing) then
begin
DrawOpacityBrush(Form1.Canvas, X, Y, clRed, 50, 85);
end;
end;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
IsDrawing := False;
end;
var
表1:TForm1;
IsDrawing:布尔型;
实施
{$R*.dfm}
过程DrawOpacityBrush(ACanvas:TCanvas;X,Y:Integer;AColor:TColor;ASize:Integer;Opacity:Byte);
变量
Bmp:TBitmap;
一、 J:整数;
像素:PRGBQuad;
ColorRgb:整数;
ColorR、ColorG、ColorB:字节;
开始
Bmp:=TBitmap.Create;
尝试
Bmp.PixelFormat:=pf32位;//需要一个alpha通道
Bmp.SetSize(ASize,ASize);
用Bmp.Canvas怎么办
开始
画笔颜色:=clFuchsia;//要遮罩的背景色
ColorRgb:=ColorToRGB(画笔颜色);
FillRect(Rect(0,0,ASize,ASize));
钢笔颜色:=一种颜色;
Pen.Style:=psSolid;
笔宽:=ASize;
MoveTo(亚细亚2区,亚细亚2区);
LineTo(亚洲区2区、亚洲区2区);
结束;
ColorR:=GetRValue(ColorRgb);
ColorG:=GetGValue(ColorRgb);
ColorB:=GetBValue(ColorRgb);
对于I:=0到Bmp.Height-1 do
开始
像素:=PRGBQuad(Bmp.ScanLine[I]);
对于J:=0到Bmp.Width-1 do
开始
用像素^do
开始
如果(rgbGreen=ColorR)和(rgbGreen=ColorG)以及(rgbBlue=ColorB),则
rgbReserved:=0
其他的
rgb:=不透明度;
//在绘制之前,必须将像素与其alpha通道预先相乘
rgbreed:=(rgbreed*rgbresered)div$FF;
rgbGreen:=(rgbGreen*rgbReserved)div$FF;
rgbBlue:=(rgbBlue*rgbReserved)div$FF;
结束;
Inc(像素);
结束;
结束;
绘制(X,Y,Bmp,255);
最后
Bmp.Free;
结束;
结束;
步骤t用于m1.FormMouseDown(发送方:ToObject;按钮:TMouseButton;
移位:t移位状态;X,Y:整数);
开始
箱子按钮
布利夫特:
开始
IsDrawing:=真;
DrawOpacityBrush(Form1.Canvas,X,Y,clRed,50,85);
结束;
结束;
结束;
过程TForm1.FormMouseMove(发送方:ToObject;Shift:TShiftState;X,
Y:整数);
开始
if(GetAsyncKeyState(VK_LBUTTON)0)和
(画外音)那么
开始
DrawOpacityBrush(Form1.Canvas,X,Y,clRed,50,85);
结束;
结束;
程序TForm1.FormMouseUp(发送方:TObject;按钮:TMouseButton;
移位:t移位状态;X,Y:整数);
开始
IsDrawing:=假;
结束;
drawDrawOpacityBrush()
过程是Remy Lebeau对我最近提出的一个问题的更新:
虽然这是可行的,但结果并不能满足我现在的需要
目前,每次在MouseMove中调用DrawOpacityBrush()
过程时,它都会继续绘制笔刷椭圆形状。这是不好的,因为根据您在画布上移动鼠标的速度,输出结果与预期不符
这些示例图像应该能够更好地说明这一点:
-我将鼠标从画布底部快速移动到顶部的第一个红色笔刷。-第二个红色笔刷我移动得慢了很多 正如您所看到的,不透明度是正确绘制的,但圆也会重复绘制 我希望它做的是:
var
Form1: TForm1;
IsDrawing: Boolean;
implementation
{$R *.dfm}
procedure DrawOpacityBrush(ACanvas: TCanvas; X, Y: Integer; AColor: TColor; ASize: Integer; Opacity: Byte);
var
Bmp: TBitmap;
I, J: Integer;
Pixels: PRGBQuad;
ColorRgb: Integer;
ColorR, ColorG, ColorB: Byte;
begin
Bmp := TBitmap.Create;
try
Bmp.PixelFormat := pf32Bit; // needed for an alpha channel
Bmp.SetSize(ASize, ASize);
with Bmp.Canvas do
begin
Brush.Color := clFuchsia; // background color to mask out
ColorRgb := ColorToRGB(Brush.Color);
FillRect(Rect(0, 0, ASize, ASize));
Pen.Color := AColor;
Pen.Style := psSolid;
Pen.Width := ASize;
MoveTo(ASize div 2, ASize div 2);
LineTo(ASize div 2, ASize div 2);
end;
ColorR := GetRValue(ColorRgb);
ColorG := GetGValue(ColorRgb);
ColorB := GetBValue(ColorRgb);
for I := 0 to Bmp.Height-1 do
begin
Pixels := PRGBQuad(Bmp.ScanLine[I]);
for J := 0 to Bmp.Width-1 do
begin
with Pixels^ do
begin
if (rgbRed = ColorR) and (rgbGreen = ColorG) and (rgbBlue = ColorB) then
rgbReserved := 0
else
rgbReserved := Opacity;
// must pre-multiply the pixel with its alpha channel before drawing
rgbRed := (rgbRed * rgbReserved) div $FF;
rgbGreen := (rgbGreen * rgbReserved) div $FF;
rgbBlue := (rgbBlue * rgbReserved) div $FF;
end;
Inc(Pixels);
end;
end;
ACanvas.Draw(X, Y, Bmp, 255);
finally
Bmp.Free;
end;
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
case Button of
mbLeft:
begin
IsDrawing := True;
DrawOpacityBrush(Form1.Canvas, X, Y, clRed, 50, 85);
end;
end;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
if (GetAsyncKeyState(VK_LBUTTON) <> 0) and
(IsDrawing) then
begin
DrawOpacityBrush(Form1.Canvas, X, Y, clRed, 50, 85);
end;
end;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
IsDrawing := False;
end;
(1)在椭圆周围绘制不透明度线
(2)有一个选项可以防止绘制任何椭圆
此模拟示例图像应给出我希望如何绘制的想法:
3条紫色刷线显示选项(1)
要实现选项(2)画笔线内的圆圈不应存在
这样你就可以在画图时花点时间,而不是在画布上疯狂地移动鼠标,希望得到你需要的结果。只有当你决定回到你刚刚做的笔刷笔划时,该区域的不透明度才会变得更暗等等
如何实现这些类型的绘图效果?
我希望能够利用TImage,因为这是我目前正在做的事情,所以在函数或过程中将TCanvas作为参数传递是理想的。我还将使用MouseDown、MouseMove和MouseUp事件进行绘图
这是我使用NGLN提供的方法得到的输出:
var
Form1: TForm1;
IsDrawing: Boolean;
implementation
{$R *.dfm}
procedure DrawOpacityBrush(ACanvas: TCanvas; X, Y: Integer; AColor: TColor; ASize: Integer; Opacity: Byte);
var
Bmp: TBitmap;
I, J: Integer;
Pixels: PRGBQuad;
ColorRgb: Integer;
ColorR, ColorG, ColorB: Byte;
begin
Bmp := TBitmap.Create;
try
Bmp.PixelFormat := pf32Bit; // needed for an alpha channel
Bmp.SetSize(ASize, ASize);
with Bmp.Canvas do
begin
Brush.Color := clFuchsia; // background color to mask out
ColorRgb := ColorToRGB(Brush.Color);
FillRect(Rect(0, 0, ASize, ASize));
Pen.Color := AColor;
Pen.Style := psSolid;
Pen.Width := ASize;
MoveTo(ASize div 2, ASize div 2);
LineTo(ASize div 2, ASize div 2);
end;
ColorR := GetRValue(ColorRgb);
ColorG := GetGValue(ColorRgb);
ColorB := GetBValue(ColorRgb);
for I := 0 to Bmp.Height-1 do
begin
Pixels := PRGBQuad(Bmp.ScanLine[I]);
for J := 0 to Bmp.Width-1 do
begin
with Pixels^ do
begin
if (rgbRed = ColorR) and (rgbGreen = ColorG) and (rgbBlue = ColorB) then
rgbReserved := 0
else
rgbReserved := Opacity;
// must pre-multiply the pixel with its alpha channel before drawing
rgbRed := (rgbRed * rgbReserved) div $FF;
rgbGreen := (rgbGreen * rgbReserved) div $FF;
rgbBlue := (rgbBlue * rgbReserved) div $FF;
end;
Inc(Pixels);
end;
end;
ACanvas.Draw(X, Y, Bmp, 255);
finally
Bmp.Free;
end;
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
case Button of
mbLeft:
begin
IsDrawing := True;
DrawOpacityBrush(Form1.Canvas, X, Y, clRed, 50, 85);
end;
end;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
if (GetAsyncKeyState(VK_LBUTTON) <> 0) and
(IsDrawing) then
begin
DrawOpacityBrush(Form1.Canvas, X, Y, clRed, 50, 85);
end;
end;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
IsDrawing := False;
end;
不透明度似乎也适用于图像,它应该只适用于多段线。为什么不画一条多段线呢
unit Unit1;
interface
uses
Windows, Classes, Graphics, Controls, Forms, ExtCtrls;
type
TPolyLine = record
Count: Integer;
Points: array of TPoint;
end;
TPolyLines = array of TPolyLine;
TForm1 = class(TForm)
PaintBox: TPaintBox;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure FormResize(Sender: TObject);
procedure PaintBoxMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure PaintBoxMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
procedure PaintBoxPaint(Sender: TObject);
private
FBlendFunc: BLENDFUNCTION;
FBmp: TBitmap;
FPolyLineCount: Integer;
FPolyLines: TPolyLines;
procedure AddPoint(APoint: TPoint);
function LastPoint: TPoint;
procedure NewPolyLine;
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.AddPoint(APoint: TPoint);
begin
with FPolyLines[FPolyLineCount - 1] do
begin
if Length(Points) = Count then
SetLength(Points, Count + 64);
Points[Count] := APoint;
Inc(Count);
end;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
FBmp := TBitmap.Create;
FBmp.Canvas.Brush.Color := clWhite;
FBmp.Canvas.Pen.Width := 30;
FBmp.Canvas.Pen.Color := clRed;
FBlendFunc.BlendOp := AC_SRC_OVER;
FBlendFunc.SourceConstantAlpha := 80;
DoubleBuffered := True;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
FBmp.Free;
end;
procedure TForm1.FormResize(Sender: TObject);
begin
FBmp.Width := PaintBox.Width;
FBmp.Height := PaintBox.Height;
end;
function TForm1.LastPoint: TPoint;
begin
with FPolyLines[FPolyLineCount - 1] do
Result := Points[Count - 1];
end;
procedure TForm1.NewPolyLine;
begin
Inc(FPolyLineCount);
SetLength(FPolyLines, FPolyLineCount);
FPolyLines[FPolyLineCount - 1].Count := 0;
end;
procedure TForm1.PaintBoxMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if ssLeft in Shift then
begin
NewPolyLine;
AddPoint(Point(X, Y));
PaintBox.Invalidate;
end;
end;
procedure TForm1.PaintBoxMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
if ssLeft in Shift then
if Sqr(LastPoint.X - X) + Sqr(LastPoint.Y - Y) > 30 then
begin
AddPoint(Point(X, Y));
PaintBox.Invalidate;
end;
end;
procedure TForm1.PaintBoxPaint(Sender: TObject);
var
R: TRect;
I: Integer;
begin
R := PaintBox.ClientRect;
FBmp.Canvas.FillRect(R);
for I := 0 to FPolyLineCount - 1 do
with FPolyLines[I] do
FBmp.Canvas.Polyline(Copy(Points, 0, Count));
Windows.AlphaBlend(PaintBox.Canvas.Handle, 0, 0, R.Right, R.Bottom,
FBmp.Canvas.Handle, 0, 0, R.Right, R.Bottom, FBlendFunc);
end;
end.
第二张图片显示了如何将其与背景相结合,并通过对代码的以下细微添加获得,而FGraphic
是一张运行时加载的图片:
procedure TForm1.PaintBoxPaint(Sender: TObject);
var
R: TRect;
I: Integer;
begin
R := PaintBox.ClientRect;
FBmp.Canvas.FillRect(R);
for I := 0 to FPolyLineCount - 1 do
with FPolyLines[I] do
FBmp.Canvas.Polyline(Copy(Points, 0, Count));
PaintBox.Canvas.StretchDraw(R, FGraphic);
Windows.AlphaBlend(PaintBox.Canvas.Handle, 0, 0, R.Right, R.Bottom,
FBmp.Canvas.Handle, 0, 0, R.Right, R.Bottom, FBlendFunc);
end;
或者,要组合已绘制的作品(如图像
),请将其画布复制到画框
:
但与David在评论中提到的一样,我也强烈建议在
画框上绘制所有内容:这就是它的用途。如何在TImage画布上绘制?我似乎只能在表单上工作。你需要一个TPaintbox而不是TImage。嗨,大卫,我真的很想在TImage上做这件事,因为到目前为止我一直在做加载/保存和在画布上绘画等工作。你需要使用一个paintbox。您当前的代码完全被破坏了,因为您是在鼠标下键而不是在绘制方法中绘制的。否。不能在鼠标事件中绘制。您必须根据WM_PAINT进行绘制。这是一条很难的规则。这意味着一个绘制
覆盖,或一个绘制框。正如我在上一篇评论中所说的,您当前的代码完全被破坏了。尝试在顶部拖动另一个窗口。“使需求更清晰”是在有人回答了手头的问题后更改问题。最好先仔细考虑一下需求,再问一个新问题。公平地说,考虑到我发布的使用TCanvas的示例,我从NGLN得到的答案不包括这个参数,而是一个不同的m