相关资料：
https://stackoverflow.com/questions/10291330/firemonkey-penmode-equivalent-drawline
https://blog.csdn.net/shuaihj/article/details/8444676
http://www.delphitop.com/html/FMX/2646.html
http://docwiki.embarcadero.com/CodeExamples/Rio/en/FMXTCanvasDrawFunctions_(Delphi)
CSDN代码下载：
https://download.csdn.net/download/zhujianqiangqq/12394005
代码实例：
1 {
2 相关资料：
3 http://www.delphitop.com/html/FMX/2646.html
4 http://docwiki.embarcadero.com/CodeExamples/Rio/en/FMXTCanvasDrawFunctions_(Delphi)
5
6 FMX 的 Canvas 在不同的系统上会分别使用:
7 WinVista、Win7: D2D (FMX.Canvas.D2D.pas)
8 WinXP: GDI+ (FMX.Canvas.GDIP.pas)
9 Mac 系列: Core Graphics (FMX.Canvas.Mac.pas)
10
11 和 HTML5 中的 Canvas 非常类似, 现在的 Canvas 模糊了 Pen 的概念:
12 之前的 Canvas.Pen 对应: Canvas.Stroke;
13 之前的 Canvas.Brush 对应: Canvas.Fill.
14
15 在 FMX 中, Canvas 无处不在, 其 Canvas.Stroke、Canvas.Fill 的状态也各不相同, 一般要先初始化它们.
16 }
17 unit Unit1;
18
19 interface
20
21 uses
22 System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
23 FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, FMX.Objects,
24 FMX.Controls.Presentation, FMX.StdCtrls, FMX.ListBox, FMX.Edit, FMX.ComboEdit,
25 FMX.Colors;
26
27 type
28 TMYStyle = record
29 StrokeColor: TAlphaColor;
30 StrokeThickness: Integer;
31 StrokeCap: TStrokeCap;
32 StrokeDash: TStrokeDash;
33 StrokeJoin: TStrokeJoin;
34 FillColor: TAlphaColor;
35 FontSize: Integer;
36 end;
37 TForm1 = class(TForm)
38 Image1: TImage;
39 DrawLine: TButton;
40 DrawEllipse: TButton;
41 DrawArc: TButton;
42 DrawBitmap: TButton;
43 GroupBox1: TGroupBox;
44 Label1: TLabel;
45 StrokeColor: TColorComboBox;
46 Label2: TLabel;
47 Label3: TLabel;
48 Label4: TLabel;
49 Label5: TLabel;
50 Label6: TLabel;
51 Label7: TLabel;
52 StrokeThickness: TEdit;
53 StrokeCap: TComboBox;
54 StrokeDash: TComboBox;
55 StrokeJoin: TComboBox;
56 FillColor: TColorComboBox;
57 FontSize: TEdit;
58 scFlat: TListBoxItem;
59 scRound: TListBoxItem;
60 sjMiter: TListBoxItem;
61 sjRound: TListBoxItem;
62 sjBevel: TListBoxItem;
63 GroupBox2: TGroupBox;
64 DrawRectSides: TButton;
65 DrawRect: TButton;
66 Edit3: TEdit;
67 FillText: TButton;
68 Claer: TButton;
69 DrawPath: TButton;
70 DrawPolygon: TButton;
71 CreateThumbnail: TButton;
72 OpenDialog1: TOpenDialog;
73 procedure DrawLineClick(Sender: TObject);
74 procedure ClaerClick(Sender: TObject);
75 procedure DrawRectSidesClick(Sender: TObject);
76 procedure Image1Paint(Sender: TObject; Canvas: TCanvas;
77 const ARect: TRectF);
78 procedure FormCreate(Sender: TObject);
79 procedure DrawArcClick(Sender: TObject);
80 procedure DrawBitmapClick(Sender: TObject);
81 procedure DrawEllipseClick(Sender: TObject);
82 procedure DrawPathClick(Sender: TObject);
83 procedure DrawPolygonClick(Sender: TObject);
84 procedure DrawRectClick(Sender: TObject);
85 procedure CreateThumbnailClick(Sender: TObject);
86 procedure FillTextClick(Sender: TObject);
87 procedure StrokeColorChange(Sender: TObject);
88 private
89 { Private declarations }
90 procedure SetMYStyle;
91 public
92 { Public declarations }
93 end;
94
95 var
96 Form1: TForm1;
97 oStyle: TMYStyle;
98
99 implementation
100 uses
101 System.UIConsts,
102 System.Math.Vectors;
103
104 {$R *.fmx}
105 {$R *.LgXhdpiPh.fmx ANDROID}
106
107 procedure TForm1.DrawLineClick(Sender: TObject);
108 var
109 p1, p2: TPointF;
110 begin
111 // sets the ends of the line to be drawn
112 p1 := TPointF.Create(20, 2);
113 p2 := TPointF.Create(350, 400);
114 Image1.Bitmap.Canvas.BeginScene;
115 SetMYStyle;
116 // draws the line on the canvas
117 Image1.Bitmap.Canvas.DrawLine(p1, p2, 100);
118 Image1.Bitmap.Canvas.EndScene;
119 end;
120
121 procedure TForm1.DrawPathClick(Sender: TObject);
122 var
123 path: TPathData;
124 MyRect1, MyRect2: TRectF;
125 begin
126 // set the circumscribed rectangle of the ellipse to be add in the path
127 MyRect1 := TRectF.Create(90, 100, 230, 300);
128 /// sets the rectangle to be add in the path
129 MyRect2 := TRectF.Create(70, 90, 220, 290);
130 // initializes and creates the path to be drawn
131 path := TPathData.Create;
132 path.AddEllipse(MyRect1);
133 path.AddRectangle(MyRect2, 0, 0, AllCorners);
134 Image1.Bitmap.Canvas.BeginScene;
135 SetMYStyle;
136 // draws the path on the canvas
137 Image1.Bitmap.Canvas.DrawPath(path, 200);
138 Image1.Bitmap.Canvas.EndScene;
139 end;
140
141 procedure TForm1.DrawPolygonClick(Sender: TObject);
142 var
143 p1, p2, p3, p4, p5, p6: TPointF;
144 MyPolygon: TPolygon; //System.Math.Vectors unit needed.
145 begin
146 // sets the points that define the polygon
147 p1 := TPointF.Create(80, 200);
148 p2 := TPointF.Create(225, 30);
149 p3 := TPointF.Create(370, 200);
150 p4 := TPointF.Create(300, 340);
151 p5 := TPointF.Create(150, 340);
152 p6 := TPointF.Create(80, 200);
153 // creates the polygon
154 SetLength(MyPolygon, 6);
155 MyPolygon[0] := p1;
156 MyPolygon[1] := p2;
157 MyPolygon[2] := p3;
158 MyPolygon[3] := p4;
159 MyPolygon[4] := p5;
160 MyPolygon[5] := p6;
161 Image1.Bitmap.Canvas.BeginScene;
162 SetMYStyle;
163 // draws the polygon on the canvas
164 Image1.Bitmap.Canvas.DrawPolygon(MyPolygon, 50);
165 Image1.Bitmap.Canvas.EndScene;
166 end;
167
168 procedure TForm1.DrawRectClick(Sender: TObject);
169 var
170 MyRect: TRectF;
171 begin
172 // sets the rectangle to be drawn
173 MyRect := TRectF.Create(50, 40, 200, 270);
174 Image1.Bitmap.Canvas.BeginScene;
175 SetMYStyle;
176 // draws the rectangle on the canvas
177 Image1.Bitmap.Canvas.DrawRect(MyRect, 30, 60, AllCorners, 100);
178 Image1.Bitmap.Canvas.EndScene;
179 end;
180
181 procedure TForm1.CreateThumbnailClick(Sender: TObject);
182 var
183 MyBitmap: TBitmap;
184 begin
185 // loads the bitmap using the TOpenDialog.
186 if OpenDialog1.Execute then
187 MyBitmap := TBitmap.CreateFromFile(OpenDialog1.Files[0]);
188 // draws a thumbnail with given sizes
189 Image1.Bitmap := MyBitmap.CreateThumbnail(300,300);
190 end;
191
192 procedure TForm1.DrawArcClick(Sender: TObject);
193 var
194 p1, p2: TPointF;
195 begin
196 // Sets the center of the arc
197 p1 := TPointF.Create(200, 200);
198 // sets the radius of the arc
199 p2 := TPointF.Create(150, 150);
200 Image1.Bitmap.Canvas.BeginScene;
201 SetMYStyle;
202 // draws the arc on the canvas
203 Image1.Bitmap.Canvas.DrawArc(p1, p2, 90, 230, 20);
204 // updates the bitmap to show the arc
205 Image1.Bitmap.Canvas.EndScene;
206 end;
207
208 procedure TForm1.DrawBitmapClick(Sender: TObject);
209 var
210 // MyBitmap is the bitmap to be drawn on the canvas
211 MyBitmap: TBitmap;
212 // is the area where to draw the bitmap
213 // also is the area of the bitmap to be drawn on the canvas
214 MyRect: TRectF;
215 begin
216 // loads the bitmap using the TOpenDialog.
217 if OpenDialog1.Execute then
218 MyBitmap := TBitmap.CreateFromFile(OpenDialog1.Files[0]);
219 // set the MyRect coordinates
220 MyRect := TRectF.Create(0, 0, 150, 200);
221 Image1.Bitmap.Canvas.BeginScene;
222 SetMYStyle;
223 // draws on the rectangle specified by MyRect the area from MyBitmap specified by MyRect
224 Image1.Bitmap.Canvas.DrawBitmap(MyBitmap, MyRect, MyRect, 20);
225 Image1.Bitmap.Canvas.EndScene;
226 end;
227
228 procedure TForm1.DrawEllipseClick(Sender: TObject);
229 var
230 MyRect: TRectF;
231 begin
232 // sets the circumscribed rectangle of the ellipse
233 MyRect := TRectF.Create(50, 40, 200, 270);
234 // draws the ellipse on the canvas
235 Image1.Bitmap.Canvas.BeginScene;
236 SetMYStyle;
237 Image1.Bitmap.Canvas.DrawEllipse(MyRect, 40);
238 Image1.Bitmap.Canvas.EndScene;
239 end;
240
241 procedure TForm1.DrawRectSidesClick(Sender: TObject);
242 var
243 MyRect: TRectF;
244 begin
245 // sets the rectangle to be customized and drawn
246 MyRect := TRectF.Create(50, 40, 200, 270);
247 Image1.Bitmap.Canvas.BeginScene;
248 SetMYStyle;
249 // customize the rectangle and draws it on the canvas
250 Image1.Bitmap.Canvas.DrawRectSides(MyRect, 50, 20, AllCorners, 40, AllSides,
251 TCornerType.Bevel);
252 Image1.Bitmap.Canvas.EndScene;
253 end;
254
255 procedure TForm1.FillTextClick(Sender: TObject);
256 var
257 MyRect: TRectF;
258 begin
259 // sets the rectangle to be customized and drawn
260 MyRect := TRectF.Create(0, 0, 100, 200);
261 Image1.Bitmap.Canvas.BeginScene;
262 SetMYStyle;
263 Image1.Bitmap.Canvas.FillText(MyRect, Edit3.Text, false, 100, [], TTextAlign.taLeading, TTextAlign.taCenter);
264 Image1.Bitmap.Canvas.EndScene;
265 end;
266
267 procedure TForm1.ClaerClick(Sender: TObject);
268 begin
269 Image1.Bitmap.Clear(TAlphaColors.White);
270 end;
271
272 procedure TForm1.FormCreate(Sender: TObject);
273 begin
274 SetMYStyle;
275 //第一种方式
276 // Self.OnPaint := Image1.OnPaint;
277 // Button1.OnPaint := Image1.OnPaint;
278 // Image1.Opacity := 0.75;
279 //第2种方式
280 Image1.Bitmap.SetSize(Round(Image1.Width), Round(Image1.Height));
281 Image1.Bitmap.Clear(TAlphaColors.White);
282 end;
283
284 procedure TForm1.Image1Paint(Sender: TObject; Canvas: TCanvas;
285 const ARect: TRectF);
286 var
287 //图片
288 oBMP: TBitmap;
289 //路径
290 oPath: TPathData;
291 MyRect1, MyRect2: TRectF;
292 //多边形
293 p1, p2, p3, p4, p5, p6: TPointF;
294 MyPolygon: TPolygon; //System.Math.Vectors unit needed.
295 begin
296 //下面的代码是第二种方式，上面几个按钮事件是第一种方式。都可以
297 // //图片
298 // oBMP := TBitMap.Create;
299 // oBMP.LoadFromFile('..\..\123.bmp');
300 // //路径
301 // MyRect1 := TRectF.Create(90, 100, 230, 300);
302 // MyRect2 := TRectF.Create(70, 90, 220, 290);
303 // oPath := TPathData.Create();
304 // oPath.AddEllipse(MyRect1);
305 // oPath.AddRectangle(MyRect2, 0, 0, AllCorners);
306 // //多边形
307 // p1 := TPointF.Create(80, 200);
308 // p2 := TPointF.Create(225, 30);
309 // p3 := TPointF.Create(370, 200);
310 // p4 := TPointF.Create(300, 340);
311 // p5 := TPointF.Create(150, 340);
312 // p6 := TPointF.Create(80, 200);
313 //
314 // SetLength(MyPolygon, 6);
315 // MyPolygon[0] := p1;
316 // MyPolygon[1] := p2;
317 // MyPolygon[2] := p3;
318 // MyPolygon[3] := p4;
319 // MyPolygon[4] := p5;
320 // MyPolygon[5] := p6;
321 //
322 // Canvas.Stroke.Kind := TBrushKind.bkSolid;
323 // Canvas.Stroke.Color := StrokeColor.Color;
324 // Canvas.Fill.Color := FillColor.Color;
325 // Canvas.Font.Size := 30;
326 // //画直线
327 // Canvas.DrawLine(ARect.Location, ARect.BottomRight, 1);
328 // //画矩形; 集合 TCorners: 四个角是否使用指定的样式类型; 枚举 TCornerType: 角样式类型
329 // Canvas.DrawRect(RectF(ARect.Width/4, ARect.Height/4, ARect.Width/4*2, ARect.Height/4*2), 0.5, 0.5, [TCorner.TopLeft], 1, TCornerType.Round);
330 // //画矩形边; 集合 TSides 指定要画的边
331 // Canvas.DrawRectSides(RectF(ARect.Width/3, ARect.Height/3, ARect.Width/3*4, ARect.Height/3*4), 0.5, 0.5,[TCorner.TopLeft], 1, [TSide.Left], TCornerType.Round);
332 // //画椭圆
333 // Canvas.DrawEllipse(RectF(ARect.Width/2, ARect.Height/2, ARect.Width/2*2, ARect.Height/2*2), 1);
334 // //画弧
335 // Canvas.DrawArc(ARect.TopLeft, ARect.BottomRight/2, 40, 40, 1);
336 // //画路径
337 // Canvas.DrawPath(oPath, 200);
338 // //画多边形
339 // Canvas.DrawPolygon(MyPolygon, 50);
340 // //图片
341 // Canvas.DrawBitmap(oBMP,
342 // RectF(0, 0, oBMP.Width, oBMP.Height),
343 // RectF(100, 100, 100 + oBMP.Width, 100 + oBMP.Height),
344 // 1);
345
346 // //填充矩形
347 // Canvas.FillRect();
348 // //填充椭圆
349 // Canvas.FillEllipse(RectF(ARect.Width/2, ARect.Height/2, ARect.Width/2*2, ARect.Height/2*2), 1);
350 // //填充弧
351 // Canvas.FillArc(ARect.TopLeft, ARect.BottomRight/2, 40, 40, 1);
352 // //填充路径
353 // Canvas.FillPath(oPath, 200);
354 // //填充多边形
355 // Canvas.FillPolygon(MyPolygon, 50);
356 // //文本输出
357 // Canvas.FillText(ARect, 'TEST测试字符串', True, 1, [], TTextAlign.taLeading, TTextAlign.taCenter);
358 // oBMP.Free
359 end;
360
361 procedure TForm1.SetMYStyle;
362 begin
363 oStyle.StrokeColor := StrokeColor.Color;
364 oStyle.StrokeThickness := StrToInt(StrokeThickness.Text);
365 case StrokeCap.ItemIndex of
366 0: oStyle.StrokeCap := TStrokeCap.Flat;
367 1: oStyle.StrokeCap := TStrokeCap.Round;
368 end;
369 case StrokeDash.ItemIndex of
370 0: oStyle.StrokeDash := TStrokeDash.Solid;
371 1: oStyle.StrokeDash := TStrokeDash.Dash;
372 2: oStyle.StrokeDash := TStrokeDash.Dot;
373 3: oStyle.StrokeDash := TStrokeDash.DashDot;
374 4: oStyle.StrokeDash := TStrokeDash.DashDotDot;
375 5: oStyle.StrokeDash := TStrokeDash.Custom;
376 end;
377 case StrokeJoin.ItemIndex of
378 0: oStyle.StrokeJoin := TStrokeJoin.Miter;
379 1: oStyle.StrokeJoin := TStrokeJoin.Round;
380 2: oStyle.StrokeJoin := TStrokeJoin.Bevel;
381 end;
382 oStyle.FillColor := FillColor.Color;
383 oStyle.FontSize := StrToInt(FontSize.Text);
384
385 Image1.Bitmap.Canvas.Stroke.Kind := TBrushKind.bkSolid;
386 Image1.Bitmap.Canvas.Stroke.Color := oStyle.StrokeColor;
387 Image1.Bitmap.Canvas.Stroke.Thickness := oStyle.StrokeThickness;
388 Image1.Bitmap.Canvas.Stroke.Cap := oStyle.StrokeCap;
389 Image1.Bitmap.Canvas.Stroke.Dash := oStyle.StrokeDash;
390 Image1.Bitmap.Canvas.Stroke.Join := oStyle.StrokeJoin;
391
392 Image1.Bitmap.Canvas.Fill.Color := oStyle.FillColor;
393 Image1.Bitmap.Canvas.Font.Size := oStyle.FontSize;
394 Image1.Bitmap.Canvas.Font.Style := [];
395 end;
396
397 procedure TForm1.StrokeColorChange(Sender: TObject);
398 begin
399 SetMYStyle;
400 end;
401
402 end.
来源：oschina
链接：https://my.oschina.net/u/4390740/blog/4269319