在画布上绘制旋转的位图

问题描述

我需要在另一个位图的画布（主位图）上绘制旋转的位图。但我不知道该怎么做。

我试着用TBitMap.Rotate方法旋转位图，然后用TCanvas.DrawBitmap方法在主要的BitMap上绘制它，但它需要很多时间（我需要绘制~100个不同角度的相同位图）：
$ b

1. 调整BMP大小
   
2. 旋转BMP


3. 在另一个画布上绘制
   

如何立即绘制不带1的旋转位图2步？

示例：

  
您应该使用转换 Matrix 而不是<$ c 
 
 
这可能看起来像： 
 
 <$> 
 p $ p>  procedure TForm1.Timer1Timer（Sender：TObject）; 
 var 
 I：Integer; 
 R：TRectF; 
 SaveMatrix：TMatrix; 
矩阵：TMatrix; 
 begin 
 MainBMP.Canvas.BeginScene; 
 MainBMP.Canvas.Clear（$ FF777777）; 
 SaveMatrix：= MainBmp.Canvas.Matrix; 
 for I：= 1 to 1000 do 
 begin 
 BuffBMP.Assign（SomeItem）; 
 R：= RectF（0，0，BuffBMP.Width，BuffBMP.Height）; 
 Matrix：= CreateRotationMatrix（DegToRad（Random（360）））; 
 Matrix.m31：=随机（1200）; 
 Matrix.m32：=随机（600）; 
 MainBMP.Canvas.SetMatrix（Matrix）; 
 MainBMP.Canvas.DrawBitmap（buffBMP，R，R，1，True）; 
 end; 
 MainBMP.Canvas.SetMatrix（SaveMatrix）; 
 MainBMP.Canvas.EndScene; 
 Canvas.BeginScene; 
 Canvas.DrawBitmap（MainBMP，ClientRect，ClientRect，1）; 
 Canvas.EndScene; 
 end; 
  

I need to draw rotated bitmap on an another bitmap's canvas (main Bitmap). But i have no idea how.

I tried to rotate bitmap with TBitMap.Rotate method and then draw it on main BitMap with TCanvas.DrawBitmap method, but it takes a lot of time (i need to draw ~100 same Bitmaps with different angles):

1. resize BMP
2. rotate BMP
3. draw on another canvas

How to immediately draw rotated bitmap without 1 and 2 steps?

Example:

var
  Form1: TForm1;
  MainBMP: TBitMap;
  SomeItem: TBitMap;
  buffBMP: TBitMap;

implementation

{$R *.fmx}


procedure TForm1.FormCreate(Sender: TObject);
begin
  MainBMP := TBitMap.Create;
  MainBMP.SetSize(screen.Width, screen.Height);
  SomeItem := TBitMap.Create;
  SomeItem.SetSize(50, 50);
  with SomeItem.Canvas do
  begin
    BeginScene;
    FillRect(rectF(0, 0, 50, 50), 5, 20, allCorners, 1);
    EndScene;
  end;
  buffBMP := TBitMap.Create;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
var
  i: integer;
  rect, sizeRect: TRectF;
begin
  MainBMP.Canvas.BeginScene;
  MainBMP.Canvas.Clear($FF777777);
  for i := 1 to 10000 do
  begin
    buffBMP.Assign(SomeItem);
    buffBMP.Rotate(random(360));
    sizeRect := rectF(0, 0, buffBMP.Width, buffBMP.Height);
    rect := sizeRect;
    rect.Offset(random(1200), random(600));
    MainBMP.Canvas.DrawBitmap(buffBMP, sizeRect, rect, 1);
  end;
  MainBMP.Canvas.EndScene;
  Form1.Canvas.BeginScene;
  Form1.Canvas.DrawBitmap(MainBMP, ClientRect, ClientRect, 1);
  Form1.Canvas.EndScene;
end;

without

buffBMP.Rotate(random(360));

it takes 16-32 ms. With this method: ~8500 ms

I'm searching for some method like

TCanvas.DrawBitmap(const ABitmap: TBitmap; const SrcRect, DstRect: TRectF; const AOpacity: Single; const HighSpeed: Boolean);

but with added Angle: single parametr

Android. FMX.

Thanks.

解决方案

You should use a transformation Matrix instead of the Rotate method on the bitmap.

Such could look like:

procedure TForm1.Timer1Timer(Sender: TObject);
var
  I: Integer;
  R: TRectF;
  SaveMatrix: TMatrix;
  Matrix: TMatrix;
begin
  MainBMP.Canvas.BeginScene;
  MainBMP.Canvas.Clear($FF777777);
  SaveMatrix := MainBmp.Canvas.Matrix;
  for I := 1 to 1000 do
  begin
    BuffBMP.Assign(SomeItem);
    R := RectF(0, 0, BuffBMP.Width, BuffBMP.Height);
    Matrix := CreateRotationMatrix(DegToRad(Random(360)));
    Matrix.m31 := Random(1200);
    Matrix.m32 := Random(600);
    MainBMP.Canvas.SetMatrix(Matrix);
    MainBMP.Canvas.DrawBitmap(buffBMP, R, R, 1, True);
  end;
  MainBMP.Canvas.SetMatrix(SaveMatrix);
  MainBMP.Canvas.EndScene;
  Canvas.BeginScene;
  Canvas.DrawBitmap(MainBMP, ClientRect, ClientRect, 1);
  Canvas.EndScene;
end;

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