笔记10: 变换图像

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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.DrawingPublic 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, 0, 80, 80))        '取原始图部分进行画(无缩放）        gr.TranslateTransform(100, 0)        gr.DrawImage(bm, 0, 0, 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, New Rectangle(0, 0, 100, 110), New RectangleF(0, 30, 60, 60), GraphicsUnit.Pixel)    End SubEnd Class

'02.Clone 克隆'克隆受参数像素格式影响，成图不同Imports System.DrawingPublic 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, New Point(10, 5))        Dim bm1 As Bitmap = bm.Clone(New Rectangle(0, 0, 40, 50), Imaging.PixelFormat.Format24bppRgb)        gr.TranslateTransform(180, 5)        gr.DrawImage(bm1, 0, 0) '为了看清clone不再缩放        Dim bm2 As Bitmap = bm.Clone(New Rectangle(40, 40, 80, 50), Imaging.PixelFormat.Format24bppRgb)        gr.TranslateTransform(80, 0)        gr.DrawImage(bm2, 0, 0)        '下面是像素不同时的展现        Dim bm3 As Bitmap = bm.Clone(New Rectangle(40, 40, 100, 60), Imaging.PixelFormat.Format16bppArgb1555)        gr.TranslateTransform(-250, 150)        gr.DrawImage(bm3, 0, 0)        Dim bm4 As Bitmap = bm.Clone(New Rectangle(40, 40, 100, 60), Imaging.PixelFormat.Format4bppIndexed)        gr.TranslateTransform(110, 0)        gr.DrawImage(bm4, 0, 0)        Dim bm5 As Bitmap = bm.Clone(New Rectangle(40, 40, 100, 60), Imaging.PixelFormat.Format1bppIndexed)        gr.TranslateTransform(110, 0)        gr.DrawImage(bm5, 0, 0)        Dim bm6 As Bitmap = bm.Clone(New Rectangle(40, 40, 100, 60), Imaging.PixelFormat.Format8bppIndexed)        gr.TranslateTransform(110, 0)        gr.DrawImage(bm6, 0, 0)    End SubEnd Class

'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.Drawing2DPublic 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, 10, bm.Width, bm.Height)) '原来的外框    End SubEnd Class

'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.DrawingImports System.Drawing.Drawing2DPublic 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, 10)        gr.DrawEllipse(myPen, New Rectangle(40, 30, 200, 100))    End SubEnd Class

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, New Point(0, 130))        img.RotateFlip(RotateFlipType.RotateNoneFlipY) '6.Y翻转        gr.DrawImage(img, New Point(130, 130))        img.Save("D:\11.bmp") '最后形变    End SubEnd Class

'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.DrawingImports System.Drawing.Drawing2DPublic 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(0, 50), New Point(200, 50)}                gr.DrawImage(bm, New Point(0, 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, New Point(0, 150)) '再把bm1画上窗体上        bm1.Save("D:\11.jpg") '变形图形存盘    End SubEnd Class

'07.插值模式缩放 Graphics.InterPolationModeImports System.DrawingImports System.Drawing.Drawing2DPublic 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, 0, bm.Width, bm.Height)        Dim dec As New Rectangle(0, 0, 0.5 * bm.Width, 0.5 * bm.Height)        gr.DrawImage(bm, 0, 0, src, GraphicsUnit.Pixel) '原图        gr.TranslateTransform(160, 0)        gr.DrawImage(bm, dec, src, GraphicsUnit.Pixel) '缺省        gr.InterpolationMode = Drawing2D.InterpolationMode.Bicubic        gr.TranslateTransform(80, 0)        gr.DrawImage(bm, dec, src, GraphicsUnit.Pixel)        gr.InterpolationMode = Drawing2D.InterpolationMode.High        gr.TranslateTransform(80, 0)        gr.DrawImage(bm, dec, src, GraphicsUnit.Pixel)        gr.InterpolationMode = Drawing2D.InterpolationMode.Low        gr.TranslateTransform(80, 0)        gr.DrawImage(bm, dec, src, GraphicsUnit.Pixel)    End SubEnd Class

'08.纹理填充图形（如椭圆）'主要用TextureBrush，并可对纹理缩放Imports System.DrawingImports System.Drawing.Drawing2DPublic 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, New Rectangle(0, 0, 300, 150))        tBrush.ScaleTransform(0.5F, 0.5F) '可对纹理进行缩放等坐标变换        gr.FillEllipse(tBrush, New Rectangle(0, 150, 300, 150))    End SubEnd Class

'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.DrawingImports System.Drawing.Drawing2DPublic 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, 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, New Rectangle(0, 0, 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, New Rectangle(0, 0, 60, 20))    End SubEnd Class

'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.Drawing2DPublic 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, New Rectangle(0, 0, 50, 50))        gc2 = gr.BeginContainer        gr.TranslateTransform(50, 50)        gr.FillRectangle(Brushes.Red, New Rectangle(0, 0, 50, 60))        gr.EndContainer(gc2)        gr.FillRectangle(Brushes.Black, New Rectangle(0, 0, 30, 40))        gr.EndContainer(gc1)        gr.FillRectangle(Brushes.Red, New Rectangle(0, 0, 20, 30))    End SubEnd Class