創(chuàng)建繪圖表面
創(chuàng)建繪圖表面有兩種常用的方法。下面設(shè)法得到PictureBox的繪圖表面。
private void Form1_Load(object sender, System.EventArgs e)
{
//得到pictureBox1的繪圖表面
Graphics g = this.pictureBox1.CreateGraphics();
}
private void pictureBox1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
//得到pictureBox1的繪圖表面
Graphics g = e.Graphics;
}
可以利用Graphics對(duì)象繪制出各種圖形圖案�？丶�Paint事件和OnPaint方法都可以繪圖都是好時(shí)機(jī)。在OnPaint方法里繪制圖案一定從參數(shù)e里面得到Graphics屬性。下面是兩個(gè)例子。
protected override void OnPaint(PaintEventArgs e)
{
e.Graphics.Clear(Color.White);
float x, y, w, h;
x = this.Left+2;
y = this.Top+2;
w = this.Width-4;
h = this.Height-4;
Pen pen = new Pen(Color.Red, 2);
e.Graphics.DrawRectangle(pen, x, y, w, h);
base.OnPaint (e);
}
private void PictureBoxII_Resize(object sender, EventArgs e)
{
this.Invalidate();
}
private void button1_Click(object sender, System.EventArgs e)
{
this.pictureBoxII1.CreateGraphics().FillEllipse(
Brushes.Blue, 10, 20, 50, 100);
}
和文本有關(guān)的三個(gè)類：
FontFamily——定義有著相似的基本設(shè)計(jì)但在形式上有某些差異的一組字樣。無法繼承此類。
Font——定義特定的文本格式，包括字體、字號(hào)和字形屬性。無法繼承此類。
StringFormat——封裝文本布局信息（如對(duì)齊方式和行距），顯示操作（如省略號(hào)插入和國家標(biāo)準(zhǔn) (National) 數(shù)字位替換）和 OpenType 功能。無法繼承此類。
下面的程序顯示了一段文字。
private void button2_Click(object sender, System.EventArgs e)
{
Graphics g = this.pictureBoxII1.CreateGraphics();
g.FillRectangle(Brushes.White, this.pictureBoxII1.ClientRectangle);
string s = "aaaaaaaaaaaaaaaaaaaaaaaaaa";
FontFamily fm = new FontFamily("ËÎÌå");
Font f = new Font(fm, 20, FontStyle.Bold, GraphicsUnit.Point);
RectangleF rectF = new RectangleF(30, 20, 180, 205);
StringFormat sf = new StringFormat();
SolidBrush sbrush = new SolidBrush(Color.FromArgb(255, 0, 0, 255));
sf.LineAlignment = StringAlignment.Center;
sf.FormatFlags = StringFormatFlags.DirectionVertical;
g.DrawString(s, f, sbrush, rectF, sf);
}
GDI+的路徑——GraphicsPath類
GraphicsPath類提供了一系列屬性和方法，利用它可以獲取路徑上的關(guān)鍵點(diǎn)，可以添加直線段、圓等幾何元素。可以獲得包圍矩形，進(jìn)行拾取測(cè)試。這些功能都怎么用，要仔細(xì)看一下。
private void button3_Click(object sender, System.EventArgs e)
{
//繪圖表面
Graphics g = this.pictureBoxII1.CreateGraphics();
//填充成白色
g.FillRectangle(Brushes.White, this.ClientRectangle);
//弄一個(gè)繪圖路徑¶
GraphicsPath gp = new GraphicsPath();
//添加一些集合圖形
gp.AddEllipse(20, 20, 300, 200);
gp.AddPie(50, 100, 300, 100, 45, 200);
gp.AddRectangle(new Rectangle(100, 30, 100, 80));
//在繪圖表面上繪制繪圖路徑
g.DrawPath(Pens.Blue, gp);
//平移
g.TranslateTransform(200, 20);
//填充繪圖路徑¶
g.FillPath(Brushes.GreenYellow, gp);
gp.Dispose();
}
區(qū)域——Region類
從已有的矩形和路徑可以創(chuàng)建Region。使用Graphics.FillRegion方法繪制Region。該類指示由矩形和由路徑構(gòu)成的圖形形狀的內(nèi)部。無法繼承此類。
漸變色填充
需要使用兩個(gè)刷子：
線性梯度刷子(LinearGradientBrush)
路徑梯度刷子(PathGuadientBrush)
private void button4_Click(object sender, System.EventArgs e)
{
//繪圖表面
Graphics g = this.pictureBoxII1.CreateGraphics();
g.FillRectangle(Brushes.White, this.pictureBoxII1.ClientRectangle);
//定義一個(gè)線性梯度刷子
LinearGradientBrush lgbrush =
new LinearGradientBrush(
new Point(0, 10),
new Point(150, 10),
Color.FromArgb(255, 0, 0),
Color.FromArgb(0, 255, 0));
Pen pen = new Pen(lgbrush);
//用線性筆刷梯度效果的筆繪制一條直線段并填充一個(gè)矩形
g.DrawLine(pen, 10, 130, 500, 130);
g.FillRectangle(lgbrush, 10, 150, 370, 30);
//定義路徑并添加一個(gè)橢圓
GraphicsPath gp = new GraphicsPath();
gp.AddEllipse(10, 10, 200, 100);
//用該路徑定義路徑梯度刷子
PathGradientBrush brush =
new PathGradientBrush(gp);
//顏色數(shù)組
Color[] colors = {
Color.FromArgb(255, 0, 0),
Color.FromArgb(100, 100, 100),
Color.FromArgb(0, 255, 0),
Color.FromArgb(0, 0, 255)};
//定義顏色漸變比率
float[] r = {0.0f, 0.3f, 0.6f, 1.0f};
ColorBlend blend = new ColorBlend();
blend.Colors = colors;
blend.Positions = r;
brush.InterpolationColors = blend;
//在橢圓外填充一個(gè)矩形
g.FillRectangle(brush, 0, 0, 210, 110);
//用添加了橢圓的路徑定義第二個(gè)路徑梯度刷子
GraphicsPath gp2 = new GraphicsPath();
gp2.AddEllipse(300, 0, 200, 100);
PathGradientBrush brush2 = new PathGradientBrush(gp2);
//設(shè)置中心點(diǎn)位置和顏色
brush2.CenterPoint = new PointF(450, 50);
brush2.CenterColor = Color.FromArgb(0, 255, 0);
//設(shè)置邊界顏色
Color[] color2 = {Color.FromArgb(255, 0, 0)};
brush2.SurroundColors = color2;
//用第二個(gè)梯度刷填充橢圓
g.FillEllipse(brush2, 300, 0, 200, 100);
}
GDI+的坐標(biāo)系統(tǒng)
通用坐標(biāo)系——用戶自定義坐標(biāo)系。
頁面坐標(biāo)系——虛擬坐標(biāo)系。
設(shè)備坐標(biāo)系——屏幕坐標(biāo)系。
當(dāng)頁面坐標(biāo)系和設(shè)備坐標(biāo)系的單位都是象素時(shí)，它們相同。
private void button10_Click(object sender, System.EventArgs e)
{
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
this.Draw(g);
}
private void Draw(Graphics g)
{
g.DrawLine(Pens.Black, 10, 10, 100, 100);
g.DrawEllipse(Pens.Black, 50, 50, 200, 100);
g.DrawArc(Pens.Black, 100, 10, 100, 100, 20, 160);
g.DrawRectangle(Pens.Green, 50, 200, 150, 100);
}
private void button5_Click(object sender, System.EventArgs e)
{
//左移
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
g.TranslateTransform(-50, 0);
this.Draw(g);
}
private void button6_Click(object sender, System.EventArgs e)
{
//右移
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
g.TranslateTransform(50, 0);
this.Draw(g);
}
private void button7_Click(object sender, System.EventArgs e)
{
//旋轉(zhuǎn)
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
g.RotateTransform(-30);
this.Draw(g);
}
private void button8_Click(object sender, System.EventArgs e)
{
//放大
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
g.ScaleTransform(1.2f, 1.2f);
this.Draw(g);
}
private void button9_Click(object sender, System.EventArgs e)
{
//縮小
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
g.ScaleTransform(0.8f, 0.8f);
this.Draw(g);
}
全局坐標(biāo)——變換對(duì)于繪圖表面上的每個(gè)圖元都會(huì)產(chǎn)生影響。通常用于設(shè)定通用坐標(biāo)系。
一下程序?qū)⒃ㄒ苿?dòng)到控件中心，并且Y軸正向朝上。
//先畫一個(gè)圓
Graphics g = e.Graphics;
g.FillRectangle(Brushes.White, this.ClientRectangle);
g.DrawEllipse(Pens.Black, -100, -100, 200, 200);
//使y軸正向朝上，必須做相對(duì)于x軸鏡像
//變換矩陣為[1,0,0,-1,0,0]
Matrix mat = new Matrix(1, 0, 0, -1, 0, 0);
g.Transform = mat;
Rectangle rect = this.ClientRectangle;
int w = rect.Width;
int h = rect.Height;
g.TranslateTransform(w/2, -h/2);
//以原點(diǎn)為中心，做一個(gè)半徑為100的圓
g.DrawEllipse(Pens.Red, -100, -100, 200, 200);
g.TranslateTransform(100, 100);
g.DrawEllipse(Pens.Green, -100, -100, 200, 200);
g.ScaleTransform(2, 2);
g.DrawEllipse(Pens.Blue, -100, -100, 200, 200);
局部坐標(biāo)系——只對(duì)某些圖形進(jìn)行變換，而其它圖形元素不變。
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
//客戶區(qū)設(shè)置為白色
g.FillRectangle(Brushes.White, this.ClientRectangle);
//y軸朝上
Matrix mat = new Matrix(1, 0, 0, -1, 0, 0);
g.Transform = mat;
//移動(dòng)坐標(biāo)原點(diǎn)到窗體中心
Rectangle rect = this.ClientRectangle;
int w = rect.Width;
int h = rect.Height;
g.TranslateTransform(w/2, -h/2);
//在全局坐標(biāo)下繪制橢圓
g.DrawEllipse(Pens.Red, -100, -100, 200, 200);
g.FillRectangle(Brushes.Black, -108, 0, 8, 8);
g.FillRectangle(Brushes.Black, 100, 0, 8, 8);
g.FillRectangle(Brushes.Black, 0, 100, 8, 8);
g.FillRectangle(Brushes.Black, 0, -108, 8, 8);
//創(chuàng)建一個(gè)橢圓然后在局部坐標(biāo)系中進(jìn)行變換
GraphicsPath gp = new GraphicsPath();
gp.AddEllipse(-100, -100, 200, 200);
Matrix mat2 = new Matrix();
//平移
mat2.Translate(150, 150);
//旋轉(zhuǎn)
mat2.Rotate(30);
gp.Transform(mat2);
g.DrawPath(Pens.Blue, gp);
PointF[] p = gp.PathPoints;
g.FillRectangle(Brushes.Black, p[0].X-2, p[0].Y+2, 4, 4);
g.FillRectangle(Brushes.Black, p[3].X-2, p[3].Y+2, 4, 4);
g.FillRectangle(Brushes.Black, p[6].X-4, p[6].Y-4, 4, 4);
g.FillRectangle(Brushes.Black, p[9].X-4, p[9].Y-4, 4, 4);
gp.Dispose();
//base.OnPaint (e);
}
Alpha混合
Color.FromArgb()的A就是Alpha。Alpha的取值范圍從0到255。0表示完全透明，255完全不透明。
當(dāng)前色＝前景色×alpha/255+背景色×（255－alpha）/255
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
//創(chuàng)建一個(gè)填充矩形
SolidBrush brush = new SolidBrush(Color.BlueViolet);
g.FillRectangle(brush, 180, 70, 200, 150);
//創(chuàng)建一個(gè)位圖，其中兩個(gè)位圖之間有透明效果
Bitmap bm1 = new Bitmap(200, 100);
Graphics bg1 = Graphics.FromImage(bm1);
SolidBrush redBrush =
new SolidBrush(Color.FromArgb(210, 255, 0, 0));
SolidBrush greenBrush =
new SolidBrush(Color.FromArgb(210, 0, 255, 0));
bg1.FillRectangle(redBrush, 0, 0, 150, 70);
bg1.FillRectangle(greenBrush, 30, 30, 150, 70);
g.DrawImage(bm1, 100, 100);
//創(chuàng)建一個(gè)位圖，其中兩個(gè)位圖之間沒有透明效果
Bitmap bm2 = new Bitmap(200, 100);
Graphics bg2 = Graphics.FromImage(bm2);
bg2.CompositingMode = CompositingMode.SourceCopy;
bg2.FillRectangle(redBrush, 0, 0, 150, 170);
bg2.FillRectangle(greenBrush, 30, 30, 150, 70);
g.CompositingQuality = CompositingQuality.GammaCorrected;
g.DrawImage(bm2, 300, 200);
//base.OnPaint (e);
}
反走樣
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
//放大8倍
g.ScaleTransform(8, 8);
//沒有反走樣的圖形和文字
Draw(g);
//設(shè)置反走樣
g.SmoothingMode = SmoothingMode.AntiAlias;
//右移40
g.TranslateTransform(40, 0);
//再繪制就是反走樣之后的了
Draw(g);
//base.OnPaint (e);
}
private void Draw(Graphics g)
{
//繪制圖形和文字
g.DrawLine(Pens.Gray, 10, 10, 40, 20);
g.DrawEllipse(Pens.Gray, 20, 20, 30, 10);
string s = "反走樣測(cè)試";
Font font = new Font("宋體", 5);
SolidBrush brush = new SolidBrush(Color.Gray);
g.DrawString(s, font, brush, 10, 40);
}
完了。暫時(shí)先總結(jié)那么多。以后發(fā)現(xiàn)必要的可以再補(bǔ)充。
GDI+編程10個(gè)基本技巧
創(chuàng)建繪圖表面
創(chuàng)建繪圖表面有兩種常用的方法。下面設(shè)法得到PictureBox的繪圖表面。
private void Form1_Load(object sender, System.EventArgs e)
{
//得到pictureBox1的繪圖表面
Graphics g = this.pictureBox1.CreateGraphics();
}
private void pictureBox1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
//得到pictureBox1的繪圖表面
Graphics g = e.Graphics;
}
可以利用Graphics對(duì)象繪制出各種圖形圖案�？丶�Paint事件和OnPaint方法都可以繪圖都是好時(shí)機(jī)。在OnPaint方法里繪制圖案一定從參數(shù)e里面得到Graphics屬性。下面是兩個(gè)例子。
protected override void OnPaint(PaintEventArgs e)
{
e.Graphics.Clear(Color.White);
float x, y, w, h;
x = this.Left+2;
y = this.Top+2;
w = this.Width-4;
h = this.Height-4;
Pen pen = new Pen(Color.Red, 2);
e.Graphics.DrawRectangle(pen, x, y, w, h);
base.OnPaint (e);
}
private void PictureBoxII_Resize(object sender, EventArgs e)
{
this.Invalidate();
}
private void button1_Click(object sender, System.EventArgs e)
{
this.pictureBoxII1.CreateGraphics().FillEllipse(
Brushes.Blue, 10, 20, 50, 100);
}
和文本有關(guān)的三個(gè)類：
FontFamily——定義有著相似的基本設(shè)計(jì)但在形式上有某些差異的一組字樣。無法繼承此類。
Font——定義特定的文本格式，包括字體、字號(hào)和字形屬性。無法繼承此類。
StringFormat——封裝文本布局信息（如對(duì)齊方式和行距），顯示操作（如省略號(hào)插入和國家標(biāo)準(zhǔn) (National) 數(shù)字位替換）和 OpenType 功能。無法繼承此類。
下面的程序顯示了一段文字。
private void button2_Click(object sender, System.EventArgs e)
{
Graphics g = this.pictureBoxII1.CreateGraphics();
g.FillRectangle(Brushes.White, this.pictureBoxII1.ClientRectangle);
string s = "aaaaaaaaaaaaaaaaaaaaaaaaaa";
FontFamily fm = new FontFamily("ËÎÌå");
Font f = new Font(fm, 20, FontStyle.Bold, GraphicsUnit.Point);
RectangleF rectF = new RectangleF(30, 20, 180, 205);
StringFormat sf = new StringFormat();
SolidBrush sbrush = new SolidBrush(Color.FromArgb(255, 0, 0, 255));
sf.LineAlignment = StringAlignment.Center;
sf.FormatFlags = StringFormatFlags.DirectionVertical;
g.DrawString(s, f, sbrush, rectF, sf);
}
GDI+的路徑——GraphicsPath類
GraphicsPath類提供了一系列屬性和方法，利用它可以獲取路徑上的關(guān)鍵點(diǎn)，可以添加直線段、圓等幾何元素�？梢垣@得包圍矩形，進(jìn)行拾取測(cè)試。這些功能都怎么用，要仔細(xì)看一下。
private void button3_Click(object sender, System.EventArgs e)
{
//繪圖表面
Graphics g = this.pictureBoxII1.CreateGraphics();
//填充成白色
g.FillRectangle(Brushes.White, this.ClientRectangle);
//弄一個(gè)繪圖路徑¶
GraphicsPath gp = new GraphicsPath();
//添加一些集合圖形
gp.AddEllipse(20, 20, 300, 200);
gp.AddPie(50, 100, 300, 100, 45, 200);
gp.AddRectangle(new Rectangle(100, 30, 100, 80));
//在繪圖表面上繪制繪圖路徑
g.DrawPath(Pens.Blue, gp);
//平移
g.TranslateTransform(200, 20);
//填充繪圖路徑¶
g.FillPath(Brushes.GreenYellow, gp);
gp.Dispose();
}
區(qū)域——Region類
從已有的矩形和路徑可以創(chuàng)建Region。使用Graphics.FillRegion方法繪制Region。該類指示由矩形和由路徑構(gòu)成的圖形形狀的內(nèi)部。無法繼承此類。
漸變色填充
需要使用兩個(gè)刷子：
線性梯度刷子(LinearGradientBrush)
路徑梯度刷子(PathGuadientBrush)
private void button4_Click(object sender, System.EventArgs e)
{
//繪圖表面
Graphics g = this.pictureBoxII1.CreateGraphics();
g.FillRectangle(Brushes.White, this.pictureBoxII1.ClientRectangle);
//定義一個(gè)線性梯度刷子
LinearGradientBrush lgbrush =
new LinearGradientBrush(
new Point(0, 10),
new Point(150, 10),
Color.FromArgb(255, 0, 0),
Color.FromArgb(0, 255, 0));
Pen pen = new Pen(lgbrush);
//用線性筆刷梯度效果的筆繪制一條直線段并填充一個(gè)矩形
g.DrawLine(pen, 10, 130, 500, 130);
g.FillRectangle(lgbrush, 10, 150, 370, 30);
//定義路徑并添加一個(gè)橢圓
GraphicsPath gp = new GraphicsPath();
gp.AddEllipse(10, 10, 200, 100);
//用該路徑定義路徑梯度刷子
PathGradientBrush brush =
new PathGradientBrush(gp);
//顏色數(shù)組
Color[] colors = {
Color.FromArgb(255, 0, 0),
Color.FromArgb(100, 100, 100),
Color.FromArgb(0, 255, 0),
Color.FromArgb(0, 0, 255)};
//定義顏色漸變比率
float[] r = {0.0f, 0.3f, 0.6f, 1.0f};
ColorBlend blend = new ColorBlend();
blend.Colors = colors;
blend.Positions = r;
brush.InterpolationColors = blend;
//在橢圓外填充一個(gè)矩形
g.FillRectangle(brush, 0, 0, 210, 110);
//用添加了橢圓的路徑定義第二個(gè)路徑梯度刷子
GraphicsPath gp2 = new GraphicsPath();
gp2.AddEllipse(300, 0, 200, 100);
PathGradientBrush brush2 = new PathGradientBrush(gp2);
//設(shè)置中心點(diǎn)位置和顏色
brush2.CenterPoint = new PointF(450, 50);
brush2.CenterColor = Color.FromArgb(0, 255, 0);
//設(shè)置邊界顏色
Color[] color2 = {Color.FromArgb(255, 0, 0)};
brush2.SurroundColors = color2;
//用第二個(gè)梯度刷填充橢圓
g.FillEllipse(brush2, 300, 0, 200, 100);
}
GDI+的坐標(biāo)系統(tǒng)
通用坐標(biāo)系——用戶自定義坐標(biāo)系。
頁面坐標(biāo)系——虛擬坐標(biāo)系。
設(shè)備坐標(biāo)系——屏幕坐標(biāo)系。
當(dāng)頁面坐標(biāo)系和設(shè)備坐標(biāo)系的單位都是象素時(shí)，它們相同。
private void button10_Click(object sender, System.EventArgs e)
{
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
this.Draw(g);
}
private void Draw(Graphics g)
{
g.DrawLine(Pens.Black, 10, 10, 100, 100);
g.DrawEllipse(Pens.Black, 50, 50, 200, 100);
g.DrawArc(Pens.Black, 100, 10, 100, 100, 20, 160);
g.DrawRectangle(Pens.Green, 50, 200, 150, 100);
}
private void button5_Click(object sender, System.EventArgs e)
{
//左移
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
g.TranslateTransform(-50, 0);
this.Draw(g);
}
private void button6_Click(object sender, System.EventArgs e)
{
//右移
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
g.TranslateTransform(50, 0);
this.Draw(g);
}
private void button7_Click(object sender, System.EventArgs e)
{
//旋轉(zhuǎn)
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
g.RotateTransform(-30);
this.Draw(g);
}
private void button8_Click(object sender, System.EventArgs e)
{
//放大
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
g.ScaleTransform(1.2f, 1.2f);
this.Draw(g);
}
private void button9_Click(object sender, System.EventArgs e)
{
//縮小
Graphics g = this.pictureBoxII1.CreateGraphics();
g.Clear(Color.White);
g.ScaleTransform(0.8f, 0.8f);
this.Draw(g);
}
全局坐標(biāo)——變換對(duì)于繪圖表面上的每個(gè)圖元都會(huì)產(chǎn)生影響。通常用于設(shè)定通用坐標(biāo)系。
一下程序?qū)⒃ㄒ苿?dòng)到控件中心，并且Y軸正向朝上。
//先畫一個(gè)圓
Graphics g = e.Graphics;
g.FillRectangle(Brushes.White, this.ClientRectangle);
g.DrawEllipse(Pens.Black, -100, -100, 200, 200);
//使y軸正向朝上，必須做相對(duì)于x軸鏡像
//變換矩陣為[1,0,0,-1,0,0]
Matrix mat = new Matrix(1, 0, 0, -1, 0, 0);
g.Transform = mat;
Rectangle rect = this.ClientRectangle;
int w = rect.Width;
int h = rect.Height;
g.TranslateTransform(w/2, -h/2);
//以原點(diǎn)為中心，做一個(gè)半徑為100的圓
g.DrawEllipse(Pens.Red, -100, -100, 200, 200);
g.TranslateTransform(100, 100);
g.DrawEllipse(Pens.Green, -100, -100, 200, 200);
g.ScaleTransform(2, 2);
g.DrawEllipse(Pens.Blue, -100, -100, 200, 200);
局部坐標(biāo)系——只對(duì)某些圖形進(jìn)行變換，而其它圖形元素不變。
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
//客戶區(qū)設(shè)置為白色
g.FillRectangle(Brushes.White, this.ClientRectangle);
//y軸朝上
Matrix mat = new Matrix(1, 0, 0, -1, 0, 0);
g.Transform = mat;
//移動(dòng)坐標(biāo)原點(diǎn)到窗體中心
Rectangle rect = this.ClientRectangle;
int w = rect.Width;
int h = rect.Height;
g.TranslateTransform(w/2, -h/2);
//在全局坐標(biāo)下繪制橢圓
g.DrawEllipse(Pens.Red, -100, -100, 200, 200);
g.FillRectangle(Brushes.Black, -108, 0, 8, 8);
g.FillRectangle(Brushes.Black, 100, 0, 8, 8);
g.FillRectangle(Brushes.Black, 0, 100, 8, 8);
g.FillRectangle(Brushes.Black, 0, -108, 8, 8);
//創(chuàng)建一個(gè)橢圓然后在局部坐標(biāo)系中進(jìn)行變換
GraphicsPath gp = new GraphicsPath();
gp.AddEllipse(-100, -100, 200, 200);
Matrix mat2 = new Matrix();
//平移
mat2.Translate(150, 150);
//旋轉(zhuǎn)
mat2.Rotate(30);
gp.Transform(mat2);
g.DrawPath(Pens.Blue, gp);
PointF[] p = gp.PathPoints;
g.FillRectangle(Brushes.Black, p[0].X-2, p[0].Y+2, 4, 4);
g.FillRectangle(Brushes.Black, p[3].X-2, p[3].Y+2, 4, 4);
g.FillRectangle(Brushes.Black, p[6].X-4, p[6].Y-4, 4, 4);
g.FillRectangle(Brushes.Black, p[9].X-4, p[9].Y-4, 4, 4);
gp.Dispose();
//base.OnPaint (e);
}
Alpha混合
Color.FromArgb()的A就是Alpha。Alpha的取值范圍從0到255。0表示完全透明，255完全不透明。
當(dāng)前色＝前景色×alpha/255+背景色×（255－alpha）/255
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
//創(chuàng)建一個(gè)填充矩形
SolidBrush brush = new SolidBrush(Color.BlueViolet);
g.FillRectangle(brush, 180, 70, 200, 150);
//創(chuàng)建一個(gè)位圖，其中兩個(gè)位圖之間有透明效果
Bitmap bm1 = new Bitmap(200, 100);
Graphics bg1 = Graphics.FromImage(bm1);
SolidBrush redBrush =
new SolidBrush(Color.FromArgb(210, 255, 0, 0));
SolidBrush greenBrush =
new SolidBrush(Color.FromArgb(210, 0, 255, 0));
bg1.FillRectangle(redBrush, 0, 0, 150, 70);
bg1.FillRectangle(greenBrush, 30, 30, 150, 70);
g.DrawImage(bm1, 100, 100);
//創(chuàng)建一個(gè)位圖，其中兩個(gè)位圖之間沒有透明效果
Bitmap bm2 = new Bitmap(200, 100);
Graphics bg2 = Graphics.FromImage(bm2);
bg2.CompositingMode = CompositingMode.SourceCopy;
bg2.FillRectangle(redBrush, 0, 0, 150, 170);
bg2.FillRectangle(greenBrush, 30, 30, 150, 70);
g.CompositingQuality = CompositingQuality.GammaCorrected;
g.DrawImage(bm2, 300, 200);
//base.OnPaint (e);
}
反走樣
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
//放大8倍
g.ScaleTransform(8, 8);
//沒有反走樣的圖形和文字
Draw(g);
//設(shè)置反走樣
g.SmoothingMode = SmoothingMode.AntiAlias;
//右移40
g.TranslateTransform(40, 0);
//再繪制就是反走樣之后的了
Draw(g);
//base.OnPaint (e);
}
private void Draw(Graphics g)
{
//繪制圖形和文字
g.DrawLine(Pens.Gray, 10, 10, 40, 20);
g.DrawEllipse(Pens.Gray, 20, 20, 30, 10);
string s = "反走樣測(cè)試";
Font font = new Font("宋體", 5);
SolidBrush brush = new SolidBrush(Color.Gray);
g.DrawString(s, font, brush, 10, 40);
}
完了。暫時(shí)先總結(jié)那么多。