一、显示图形图像
对图像文件的显示过程:
(1)创建Image类(如Bitmap)、Graphics烊的对象
(2)用Graphics.DrawImage绘制
图形文件格式:
Bmp 与存储设置和应用程序无关的图像。每位像素位数(1、4、8、15、24、32、64)在
文件头中指定。24位Bmp是通用的。
GIF Web通用格式。适用线、纯色、边界清晰图片。是无损压缩。可指定一色为透明。
JPEG 24位,有损压缩(肉眼难辨),不支持透明。
EXIF 数码相机照片格式,据JPEG压缩,还包括日期、曝光时间、相机等信息。
PNG 无损压缩(同GIF),以8、24、48位存储颜色,并以1、2、4、8、16位存储灰度
为每像素存储Alpha值。还可含Gamma及颜色校正,可精确显示图像。
TIFF 各平台及程序均支持,以每像素任意位存储图像,压缩算法多样。灵活性好
'01.DrawImage绘制图片文件 ' 共有30个重载。从原始图上的一部分或全部 画到 目标上的某位置或区域 Imports System.Drawing Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click Dim gr As Graphics = Me.CreateGraphics Dim bm As New Bitmap("D:\1.jpg") '指定位置画原始图的全部 gr.DrawImage(bm,New Point(10,5)) '指定位置区域画原始图(有缩放功能) gr.TranslateTransform(200,5) gr.DrawImage(bm,New Rectangle(0,80,80)) '取原始图部分进行画(无缩放) gr.TranslateTransform(100,0) gr.DrawImage(bm,New RectangleF(0,30,60,60),GraphicsUnit.Pixel) '取原始图部分在目标上某区域绘制(缩放) gr.TranslateTransform(-280,150) gr.DrawImage(bm,100,110),GraphicsUnit.Pixel) End Sub End Class@H_502_55@
'02.Clone 克隆 '克隆受参数像素格式影响,成图不同 Imports System.Drawing Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click Dim gr As Graphics = Me.CreateGraphics Dim bm As New Bitmap("D:\1.bmp") '原图 gr.DrawImage(bm,5)) Dim bm1 As Bitmap = bm.Clone(New Rectangle(0,40,50),Imaging.PixelFormat.Format24bppRgb) gr.TranslateTransform(180,5) gr.DrawImage(bm1,0) '为了看清clone不再缩放 Dim bm2 As Bitmap = bm.Clone(New Rectangle(40,Imaging.PixelFormat.Format24bppRgb) gr.TranslateTransform(80,0) gr.DrawImage(bm2,0) '下面是像素不同时的展现 Dim bm3 As Bitmap = bm.Clone(New Rectangle(40,Imaging.PixelFormat.Format16bppArgb1555) gr.TranslateTransform(-250,150) gr.DrawImage(bm3,0) Dim bm4 As Bitmap = bm.Clone(New Rectangle(40,Imaging.PixelFormat.Format4bppIndexed) gr.TranslateTransform(110,0) gr.DrawImage(bm4,0) Dim bm5 As Bitmap = bm.Clone(New Rectangle(40,Imaging.PixelFormat.Format1bppIndexed) gr.TranslateTransform(110,0) gr.DrawImage(bm5,0) Dim bm6 As Bitmap = bm.Clone(New Rectangle(40,Imaging.PixelFormat.Format8bppIndexed) gr.TranslateTransform(110,0) gr.DrawImage(bm6,0) End Sub End Class@H_502_55@
'03 MakeTransparent 使某色透明 ' 先取得某颜色GetPixel,然后用maketransparent进行透明 Imports System.Drawing.Drawing2D Public Class Form1 '为了便于查看,窗体背景设置为黄色 Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click Dim gr As Graphics = Me.CreateGraphics '取色 Dim bm As New Bitmap("D:\2.bmp") Dim col As Color = bm.GetPixel(1,1) '画原始图 gr.DrawImage(bm,10,10) '透明 bm.MakeTransparent(col) gr.DrawImage(bm,280,10) gr.DrawRectangle(Pens.Red,New Rectangle(280,bm.Width,bm.Height)) '原来的外框 End Sub End Class@H_502_55@
'04 用ico图像绘制图形 ' 先用ico构造TextureBrush,然后再构造Pen,最后画图形 Imports System.Drawing Imports System.Drawing.Drawing2D Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click Dim gr As Graphics = Me.CreateGraphics Dim bm As New Bitmap("d:\3.ico") Dim tb As New Drawing.TextureBrush(bm) Dim myPen As New Pen(tb,20) gr.DrawImage(bm,10) gr.DrawEllipse(myPen,New Rectangle(40,200,100)) End Sub End Class@H_502_55@
二、图像变换
1、Image对象的RotateFlip方法可以旋转和翻转。
Rotate旋转, Flip翻转
须先用Image.FromFile(Str)等方法加载图像文件
'05.图像的旋转与翻转:Image.RotateFlip
'旋转都是顺时针
Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click Dim gr As Graphics = Me.CreateGraphics Dim img As Image = Image.FromFile("D:\5.jpg") gr.DrawImage(img,New Point(0,0)) img.RotateFlip(RotateFlipType.Rotate90FlipNone) '2.顺时针转90 gr.DrawImage(img,New Point(130,0)) '每次变换都是从上一次变换 img.RotateFlip(RotateFlipType.Rotate90FlipX) '3.先转90再X翻转 gr.DrawImage(img,New Point(260,0)) img.RotateFlip(RotateFlipType.Rotate90FlipY) ' 4.先转90再Y翻转 gr.DrawImage(img,New Point(390,0)) img.RotateFlip(RotateFlipType.RotateNoneFlipX) ' 5.X翻转 gr.DrawImage(img,130)) img.RotateFlip(RotateFlipType.RotateNoneFlipY) '6.Y翻转 gr.DrawImage(img,130)) img.Save("D:\11.bmp") '最后形变 End Sub End Class@H_502_55@
'06.对图形的反射、扭曲 '关键在定义目标区域,目标区域由平行四边形定义(取三个点,第四点自动计算) '三点:左上角、左下角,右上角。 Imports System.Drawing Imports System.Drawing.Drawing2D Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click Dim bm As New Bitmap("D:\1.jpg") Dim gr As Graphics = Me.CreateGraphics Dim bm1 As New Bitmap(bm.Width,bm.Height) Dim gr1 As Graphics = Graphics.FromImage(bm1) Dim p As Point() = {New Point(100,0),New Point(200,50)} gr.DrawImage(bm,0)) '原图在窗体上 '示意图:bm上有图,通过绘制(变形)到bm1(原先有空白,现在有图),最后显示在窗体上 gr1.DrawImage(bm,p) '先把bm变形画到bm1上(要注意bm1能容纳bm变形后的图形,例中专门不能容纳全部变形后图形) gr.DrawImage(bm1,150)) '再把bm1画上窗体上 bm1.Save("D:\11.jpg") '变形图形存盘 End Sub End Class@H_502_55@
'07.插值模式缩放 Graphics.InterPolationMode Imports System.Drawing Imports System.Drawing.Drawing2D Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click Dim gr As Graphics = Me.CreateGraphics Dim bm As New Bitmap("d:\1.jpg") Dim src As New Rectangle(0,bm.Height) Dim dec As New Rectangle(0,0.5 * bm.Width,0.5 * bm.Height) gr.DrawImage(bm,src,GraphicsUnit.Pixel) '原图 gr.TranslateTransform(160,dec,GraphicsUnit.Pixel) '缺省 gr.InterpolationMode = Drawing2D.InterpolationMode.Bicubic gr.TranslateTransform(80,GraphicsUnit.Pixel) gr.InterpolationMode = Drawing2D.InterpolationMode.High gr.TranslateTransform(80,GraphicsUnit.Pixel) gr.InterpolationMode = Drawing2D.InterpolationMode.Low gr.TranslateTransform(80,GraphicsUnit.Pixel) End Sub End Class@H_502_55@
'08.纹理填充图形(如椭圆) '主要用TextureBrush,并可对纹理缩放 Imports System.Drawing Imports System.Drawing.Drawing2D Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click Dim gr As Graphics = Me.CreateGraphics Dim bm As New Bitmap("d:\1.jpg") Dim tBrush As New TextureBrush(bm) gr.FillEllipse(tBrush,300,150)) tBrush.ScaleTransform(0.5F,0.5F) '可对纹理进行缩放等坐标变换 gr.FillEllipse(tBrush,150,150)) End Sub End Class@H_502_55@
'09.Graphics.BeginContainer ' Graphics.EndContainer '图形容器:“装载”或“容纳”图形数据(包括坐标)的“容器”。比如窗口(0,0)就是默认的容器。 'BeginContainer将保存先前的容器(数据到堆栈上,并设置标识),开始新的一容器。 'EndContainer 结束当前容器,并返回上一个beginContainer保存的数据。 'EndContainer之前可以有多个BeginContainer,但只能返回上一次容器数据(并移除堆栈上数据) Imports System.Drawing Imports System.Drawing.Drawing2D Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click Dim gr As Graphics = Me.CreateGraphics Dim grContainer As GraphicsContainer '定位,便于观看后面位置变化 gr.DrawRectangle(Pens.Black,New Rectangle(50,50,50)) gr.TranslateTransform(50,50) 'A grContainer = gr.BeginContainer '存储以前数据,开始创建容器 gr.TranslateTransform(0,40) gr.FillRectangle(Brushes.Red,20,60)) gr.EndContainer(grContainer) '恢复存储前容器,所以坐标返回到A处 gr.FillRectangle(Brushes.Blue,20)) End Sub End Class@H_502_55@
'10.EndContainer(gc)还原某状态前的容器 ' gr.restore 还原原始容器,删除堆栈上的信息 Imports System.Drawing.Drawing2D Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click Dim gr As Graphics = Me.CreateGraphics Dim gc1 As GraphicsContainer Dim gc2 As GraphicsContainer gc1 = gr.BeginContainer gr.TranslateTransform(50,50) gr.FillRectangle(Brushes.Blue,50)) gc2 = gr.BeginContainer gr.TranslateTransform(50,50) gr.FillRectangle(Brushes.Red,60)) gr.EndContainer(gc2) gr.FillRectangle(Brushes.Black,40)) gr.EndContainer(gc1) gr.FillRectangle(Brushes.Red,30)) End Sub End Class @H_502_55@