知识大全 GDI+编程的10个基本技巧

Posted 2022-07-17 坐标系

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　　创建绘图表面 创建绘图表面有两种常用的方法下面设法得到PictureBox的绘图表面 private void Form _Load(object sender System EventArgs e) //得到pictureBox 的绘图表面 Graphics g = this pictureBox CreateGraphics(); private void pictureBox _Paint(object sender System Windows Forms PaintEventArgs e) //得到pictureBox 的绘图表面 Graphics g = e Graphics; 可以利用Graphics对象绘制出各种图形图案控件的Paint事件和OnPaint方法都可以绘图都是好时机在OnPaint方法里绘制图案一定从参数e里面得到Graphics属性下面是两个例子 protected override void OnPaint(PaintEventArgs e) e Graphics Clear(Color White); float x y w h; x = this Left+ ; y = this Top+ ; w = this Width ; h = this Height ; Pen pen = new Pen(Color Red ); e Graphics DrawRectangle(pen x y w h); base OnPaint (e); private void PictureBoxII_Resize(object sender EventArgs e) this Invalidate(); private void button _Click(object sender System EventArgs e) this pictureBoxII CreateGraphics() FillEllipse( Brushes Blue ); 和文本有关的三个类 FontFamily——定义有着相似的基本设计但在形式上有某些差异的一组字样无法继承此类 Font——定义特定的文本格式包括字体字号和字形属性无法继承此类 StringFormat——封装文本布局信息（如对齐方式和行距）显示操作（如省略号插入和国家标准 (National) 数字位替换）和 OpenType 功能无法继承此类下面的程序显示了一段文字 private void button _Click(object sender System EventArgs e) Graphics g = this pictureBoxII CreateGraphics(); g FillRectangle(Brushes White this pictureBoxII ClientRectangle); string s = aaaaaaaaaaaaaaaaaaaaaaaaaa ; FontFamily fm = new FontFamily( ËÎÌå ); Font f = new Font(fm FontStyle Bold GraphicsUnit Point); RectangleF rectF = new RectangleF( ); StringFormat sf = new StringFormat(); SolidBrush sbrush = new SolidBrush(Color FromArgb( )); sf LineAlignment = StringAlignment Center; sf FormatFlags = StringFormatFlags DirectionVertical; g DrawString(s f sbrush rectF sf); GDI+的路径——GraphicsPath类 GraphicsPath类提供了一系列属性和方法利用它可以获取路径上的关键点可以添加直线段圆等几何元素可以获得包围矩形进行拾取测试这些功能都怎么用要仔细看一下 private void button _Click(object sender System EventArgs e) //绘图表面 Graphics g = this pictureBoxII CreateGraphics(); //填充成白色 g FillRectangle(Brushes White this ClientRectangle); //弄一个绘图路径¶ GraphicsPath gp = new GraphicsPath(); //添加一些集合图形 gp AddEllipse( ); gp AddPie( ); gp AddRectangle(new Rectangle( )); //在绘图表面上绘制绘图路径 g DrawPath(Pens Blue gp); //平移 g TranslateTransform( ); //填充绘图路径¶ g FillPath(Brushes GreenYellow gp); gp Dispose();

　　区域——Region类 从已有的矩形和路径可以创建Region 使用Graphics FillRegion方法绘制Region 该类指示由矩形和由路径构成的图形形状的内部无法继承此类渐变色填充需要使用两个刷子线性梯度刷子(LinearGradientBrush) 路径梯度刷子(PathGuadientBrush) private void button _Click(object sender System EventArgs e)

　　//绘图表面 Graphics g = this pictureBoxII CreateGraphics(); g FillRectangle(Brushes White this pictureBoxII ClientRectangle); //定义一个线性梯度刷子 LinearGradientBrush lgbrush = new LinearGradientBrush( new Point( ) new Point( ) Color FromArgb( ) Color FromArgb( )); Pen pen = new Pen(lgbrush); //用线性笔刷梯度效果的笔绘制一条直线段并填充一个矩形 g DrawLine(pen ); g FillRectangle(lgbrush ); //定义路径并添加一个椭圆 GraphicsPath gp = new GraphicsPath(); gp AddEllipse( ); //用该路径定义路径梯度刷子 PathGradientBrush brush = new PathGradientBrush(gp); //颜色数组 Color[] colors = Color FromArgb( ) Color FromArgb( ) Color FromArgb( ) Color FromArgb( ); //定义颜色渐变比率 float[] r = f f f f; ColorBlend blend = new ColorBlend(); blend Colors = colors; blend Positions = r; brush InterpolationColors = blend; //在椭圆外填充一个矩形 g FillRectangle(brush ); //用添加了椭圆的路径定义第二个路径梯度刷子 GraphicsPath gp = new GraphicsPath(); gp AddEllipse( ); PathGradientBrush brush = new PathGradientBrush(gp ); //设置中心点位置和颜色 brush CenterPoint = new PointF( ); brush CenterColor = Color FromArgb( ); //设置边界颜色 Color[] color = Color FromArgb( ); brush SurroundColors = color ; //用第二个梯度刷填充椭圆 g FillEllipse(brush );

　　GDI+的坐标系统 通用坐标系——用户自定义坐标系页面坐标系——虚拟坐标系设备坐标系——屏幕坐标系当页面坐标系和设备坐标系的单位都是象素时它们相同 private void button _Click(object sender System EventArgs e) Graphics g = this pictureBoxII CreateGraphics(); g Clear(Color White); this Draw(g); private void Draw(Graphics g) g DrawLine(Pens Black ); g DrawEllipse(Pens Black ); g DrawArc(Pens Black ); g DrawRectangle(Pens Green ); private void button _Click(object sender System EventArgs e)

　　//左移 Graphics g = this pictureBoxII CreateGraphics(); g Clear(Color White); g TranslateTransform( ); this Draw(g); private void button _Click(object sender System EventArgs e) //右移 Graphics g = this pictureBoxII CreateGraphics(); g Clear(Color White); g TranslateTransform( ); this Draw(g); private void button _Click(object sender System EventArgs e) //旋转 Graphics g = this pictureBoxII CreateGraphics(); g Clear(Color White); g RotateTransform( ); this Draw(g); private void button _Click(object sender System EventArgs e) //放大 Graphics g = this pictureBoxII CreateGraphics(); g Clear(Color White); g ScaleTransform( f f); this Draw(g); private void button _Click(object sender System EventArgs e) //缩小 Graphics g = this pictureBoxII CreateGraphics(); g Clear(Color White); g ScaleTransform( f f); this Draw(g); 全局坐标——变换对于绘图表面上的每个图元都会产生影响通常用于设定通用坐标系一下程序将原定移动到控件中心并且Y轴正向朝上 //先画一个圆 Graphics g = e Graphics; g FillRectangle(Brushes White this ClientRectangle); g DrawEllipse(Pens Black ); //使y轴正向朝上必须做相对于x轴镜像 //变换矩阵为[ ] Matrix mat = new Matrix( ); g Transform = mat; Rectangle rect = this ClientRectangle; int w = rect Width; int h = rect Height; g TranslateTransform(w/ h/ );

　　//以原点为中心做一个半径为的圆 g DrawEllipse(Pens Red ); g TranslateTransform( ); g DrawEllipse(Pens Green ); g ScaleTransform( ); g DrawEllipse(Pens Blue ); 局部坐标系——只对某些图形进行变换而其它图形元素不变 protected override void OnPaint(PaintEventArgs e) Graphics g = e Graphics; //客户区设置为白色 g FillRectangle(Brushes White this ClientRectangle); //y轴朝上 Matrix mat = new Matrix( ); g Transform = mat; //移动坐标原点到窗体中心 Rectangle rect = this ClientRectangle; int w = rect Width; int h = rect Height; g TranslateTransform(w/ h/ );

　　//在全局坐标下绘制椭圆 g DrawEllipse(Pens Red ); g FillRectangle(Brushes Black ); g FillRectangle(Brushes Black ); g FillRectangle(Brushes Black ); g FillRectangle(Brushes Black ); //创建一个椭圆然后在局部坐标系中进行变换 GraphicsPath gp = new GraphicsPath(); gp AddEllipse( ); Matrix mat = new Matrix(); //平移 mat Translate( ); //旋转 mat Rotate( ); gp Transform(mat ); g DrawPath(Pens Blue gp); PointF[] p = gp PathPoints; g FillRectangle(Brushes Black p[ ] X p[ ] Y+ ); g FillRectangle(Brushes Black p[ ] X p[ ] Y+ ); g FillRectangle(Brushes Black p[ ] X p[ ] Y ); g FillRectangle(Brushes Black p[ ] X p[ ] Y ); gp Dispose(); //base OnPaint (e);

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