c# Graphics中绘制的内容转化为bitmap

[caixiaoqiting]

c# Graphics中绘制的内容转化为bitmap，并保存bitmap

[caixiaoqiting]

你好，我知道有在bitmap上创建一个graphics,但是我目的是单向的，就是从一个已经存在的graphics上将其绘制的内容用bitmap保存下来，例如我定义一个Graphics g=this.createGraphics()再将g中绘制的内容用bitmap保存下来;而不是Graphics g = Graphics.FromImage(bitmap）。

[caixiaoqiting]

自己顶顶，，，，

[hollandjzy]

不能反一下 现在bitmap上创建一个graphics 然后再绘制内容 结果不是一样吗

[caixiaoqiting]

我希望是一个实时变化的图像，例如第一次先画了一条直线，第二次再要画一条直线，若是用bitmap去做，那么第一次你画的直线就被重画了，第一次画的直线就不存在了。而我是希望再第一条直线上继续画第二条直线

[caixiaoqiting]

使用Graphics g=this.createGraphics()的好处就是之前的内容不会被重画，就是这样的一个好处，要不然我会直接使用bitmap去创建一个graphics的，求各位大虾帮助

[xiaoid]

        <Runtime.InteropServices.DllImport("gdi32", entrypoint:="BitBlt", ExactSpelling:=True, setlasterror:=True)> _
        Private Shared Function BitBlt(ByVal destDC As IntPtr, _
                                       ByVal x As Int32, _
                                       ByVal y As Int32, _
                                       ByVal width As Int32, _
                                       ByVal height As Int32, _
                                       ByVal sourceDC As IntPtr, _
                                       ByVal xsrc As Int32, _
                                       ByVal ysrc As Int32, _
                                       ByVal dwrop As Int32) As Int32

            'rop: 复制的模式，vbsrccopy=&HCC0020
        End Function

        <Runtime.InteropServices.DllImport("gdi32", entrypoint:="CreateCompatibleBitmap", ExactSpelling:=True, setlasterror:=True)> _
        Private Shared Function CreateCompatibleBitmap(ByVal hdc As IntPtr, _
                                                       ByVal width As Int32, _
                                                       ByVal height As Int32) As IntPtr

            '以hdc为基础创建一个新的hbitmap对象;
        End Function

        <Runtime.InteropServices.DllImport("gdi32", entrypoint:="CreateCompatibleDC", ExactSpelling:=True, setlasterror:=True)> _
        Private Shared Function CreateCompatibleDC(ByVal hdc As IntPtr) As IntPtr
            '以hdc为基础创建一个新的hdc对象;
        End Function

        <Runtime.InteropServices.DllImport("gdi32", entrypoint:="SelectObject", ExactSpelling:=True, setlasterror:=True)> _
        Private Shared Function SelectObject(ByVal hdc As IntPtr, ByVal hbitmap As IntPtr) As IntPtr
            '将hbitmap句柄和hdc配对;
        End Function
        <Runtime.InteropServices.DllImport("gdi32", entrypoint:="DeleteObject", ExactSpelling:=True, setlasterror:=True)> _
        Private Shared Function DeleteObject(ByVal hdc As IntPtr) As IntPtr
            '将hbitmap句柄和hdc配对;
        End Function



        ''' <summary>
        ''' 创建 Bitmap 对象;
        ''' </summary>
        ''' <param name="g">从 Graphics 创建 Drawing.Bitmap 对象;</param>
        ''' <returns></returns>
        ''' <remarks></remarks>
        Shared Function CreateBitmap(ByVal g As Drawing.Graphics) As Drawing.Bitmap

            Dim _img As Drawing.Bitmap

            Dim _imghandle As IntPtr
            Dim _imghdc As IntPtr

            Dim _width As Int32 = g.VisibleClipBounds.Width
            Dim _height As Int32 = g.VisibleClipBounds.Height

            '对象g的hdc;
            Dim _gdc As IntPtr = g.GetHdc

            _imghandle = CreateCompatibleBitmap(_gdc, _width, _height)
            _imghdc = CreateCompatibleDC(_gdc)

            SelectObject(_imghdc, _imghandle)

            Call BitBlt(_imghdc, 0, 0, _width, _height, _gdc, 0, 0, &HCC0020)

            g.ReleaseHdc()

            _img = Drawing.Bitmap.FromHbitmap(_imghandle)

            DeleteObject(_imghdc)
            DeleteObject(_imghandle)

            Return _img

        End Function

[caixiaoqiting]

谢谢楼上的兄弟，貌似好像对我帮助不大，谢谢哈，希望有人回答出，大家都有分，目前为止我已经写一段截屏的代码将绘制的内容截下来再用bitmap保存。不过我个人觉得有点麻烦，希望有更多的人给出好的意见和方法

[xiaoid]

无语..
我真想删了, 可惜没这个权限.

[gomoku]

倒过来想:)
从bitmap得到一个Graphics场境，绘往该Graphics的内容就自然成为bitmap的一部分了。
using(Graphics g = Graphics.FromImage(bitmap))
{
g.Draw...
}

[黄亮]

Graphics.FromImage(image);
....
image.Save(...);

[江湖我不怕]

联系我[e-mail]

[caixiaoqiting]

[Quote=引用 11 楼 caijiuxiao 的回复:]
联系我[e-mail]
[/Quote]
正解，谢谢，现在结贴