作为我正在研究的项目的一部分,我必须从图像中存储和恢复魔杖区域.为了获得存储数据,我正在使用GetRegionData方法.根据规范指定,此方法:
Returns a RegionData that represents the information that describes this Region.
我将RegionData.Data属性中保存的byte []存储在base64字符串中,所以我可以稍后通过一种非常规的方法检索RegionData:
// This "instantiates" a RegionData object by simply initiating an object and setting the object type pointer to the specified type.
// Constructors don't run, but in this very specific case - they don't have to. The RegionData's only member is a "data" byte array, which we set right after.
var regionData =
(RegionData)FormatterServices.GetUninitializedObject(typeof(RegionData));
regionData.Data = bytes;
然后我创建一个Region并在构造函数中传递上面的RegionData对象,并调用GetRegionScans来获取构成该区域的矩形对象:
var region = new Region(regionData);
RectangleF[] rectangles = region.GetRegionScans(new Matrix());
这样我最终得到了一组用于绘制和重建区域的矩形.我已将整个绘图过程隔离到WinForms应用程序,并且我使用以下代码在图像控件上绘制此矩形集合:
using (var g = Graphics.FromImage(picBox.Image))
{
var p = new Pen(Color.Black, 1f);
var alternatePen = new Pen(Color.BlueViolet, 1f);
var b = new SolidBrush(picBox.BackColor);
var niceBrush = new SolidBrush(Color.Orange);
foreach (var r in rectangles)
{
g.DrawRectangle(p,
new Rectangle(new Point((int)r.Location.X, (int)r.Location.Y),
new Size((int)r.Width, (int)r.Height)));
}
}
上面的代码导致在我的图片控件中呈现以下内容:
这里的大纲是正确的 – 这正是我最初使用魔棒工具标记的内容.然而,当我绘制矩形时,我也最终得到了水平线,这些线不是原始魔棒选择的一部分.因此,我无法再查看实际图像,而我的魔棒工具现在使图像变得无用.
我想我只会在屏幕上绘制每个矩形的左右边缘,所以我最终会在屏幕上显示一堆点,为我勾勒出图像的轮廓.为此,我尝试了以下代码:
var pointPair = new[]
{
new Point((int) r.Left, (int) r.Y),
new Point((int) r.Right, (int) r.Y)
};
g.DrawRectangle(p, pointPair[0].X, pointPair[0].Y, 1, 1);
g.DrawRectangle(p, pointPair[1].X, pointPair[1].Y, 1, 1);
结果可以在下面观察到:
虽然距离较近,但它仍然没有雪茄.
我正在寻找一种连接点的方法,以便在我的区域中创建矩形的轮廓.对人类而言微不足道的事情,但我无法弄清楚如何指导计算机为我做这件事.
我已经尝试通过计算每个矩形的左和右点上的最邻近点,并将它们渲染为单独的矩形,从每个矩形创建新点,但无济于事.
任何帮助将不胜感激,因为我真的在这里不知所措.
谢谢!
解
感谢Peter Duniho的回答,我设法解决了这个问题.为了完整起见,我在下面包含了SafeHandle包装类和我用来完成这项工作的代码.
绘图代码
下面的代码是我用来绘制区域轮廓的代码.
private void DrawRegionOutline(Graphics graphics, Color color, Region region)
{
var regionHandle = new SafeRegionHandle(region, region.GetHrgn(graphics));
var deviceContext = new SafeDeviceContextHandle(graphics);
var brushHandle = new SafeBrushHandle(color);
using (regionHandle)
using (deviceContext)
using (brushHandle)
FrameRgn(deviceContext.DangerousGetHandle(), regionHandle.DangerousGetHandle(), brushHandle.DangerousGetHandle(), 1, 1);
}
SafeHandleNative
SafeHandleZeroOrMinusOneIsInvalid周围的小包装,以确保在完成句柄后进行清理.
[HostProtection(MayLeakOnAbort = true)]
[SuppressUnmanagedCodeSecurity]
public abstract class SafeNativeHandle : SafeHandleZeroOrMinusOneIsInvalid
{
#region Platform Invoke
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
protected internal static extern bool CloseHandle(IntPtr hObject);
#endregion
/// <summary>
/// Initializes a new instance of the <see cref="SafeNativeHandle"/> class.
/// </summary>
protected SafeNativeHandle() : base(true)
{}
/// <summary>
/// Initializes a new instance of the <see cref="SafeNativeHandle"/> class.
/// </summary>
/// <param name="handle">The handle.</param>
protected SafeNativeHandle(IntPtr handle)
: base(true)
{
SetHandle(handle);
}
}
我创建了三个其他包装器,一个用于Region对象,一个用于Brush,另一个用于设备上下文句柄.这些都继承自SafeNativeHandle,但为了不垃圾邮件,我只提供我用于下面区域的那个.其他两个包装器实际上是相同的,但使用相应的Win32 API来清理自己的资源.
public class SafeRegionHandle : SafeNativeHandle
{
private readonly Region _region;
/// <summary>
/// Initializes a new instance of the <see cref="SafeRegionHandle" /> class.
/// </summary>
/// <param name="region">The region.</param>
/// <param name="handle">The handle.</param>
public SafeRegionHandle(Region region, IntPtr handle)
{
_region = region;
base.handle = handle;
}
/// <summary>
/// When overridden in a derived class, executes the code required to free the handle.
/// </summary>
/// <returns>
/// true if the handle is released successfully; otherwise, in the event of a catastrophic failure, false. In this case, it generates a releaseHandleFailed MDA Managed Debugging Assistant.
/// </returns>
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
protected override bool ReleaseHandle()
{
try
{
_region.ReleaseHrgn(handle);
}
catch
{
return false;
}
return true;
}
}
解决方法:
我还不完全确定我理解这个问题.然而,听起来好像你只是想通过概述它来绘制给定区域,而不是填充它.
不幸的是,据我所知,.NET API不支持这一点.但是,本机Windows API可以.这是一些应该做你想做的代码:
[DllImport("gdi32")]
static extern bool FrameRgn(System.IntPtr hDC, System.IntPtr hRgn, IntPtr hBrush, int nWidth, int nHeight);
[DllImport("gdi32")]
static extern IntPtr CreateSolidBrush(uint colorref);
[DllImport("gdi32.dll")]
static extern bool DeleteObject([In] IntPtr hObject);
[StructLayout(LayoutKind.Explicit)]
struct COLORREF
{
[FieldOffset(0)]
public uint colorref;
[FieldOffset(0)]
public byte red;
[FieldOffset(1)]
public byte green;
[FieldOffset(2)]
public byte blue;
public COLORREF(Color color)
: this()
{
red = color.R;
green = color.G;
blue = color.B;
}
}
void DrawRegion(Graphics graphics, Color color, Region region)
{
COLORREF colorref = new COLORREF(color);
IntPtr hdc = IntPtr.Zero, hbrush = IntPtr.Zero, hrgn = IntPtr.Zero;
try
{
hrgn = region.GetHrgn(graphics);
hdc = graphics.GetHdc();
hbrush = CreateSolidBrush(colorref.colorref);
FrameRgn(hdc, hrgn, hbrush, 1, 1);
}
finally
{
if (hrgn != IntPtr.Zero)
{
region.ReleaseHrgn(hrgn);
}
if (hbrush != IntPtr.Zero)
{
DeleteObject(hbrush);
}
if (hdc != IntPtr.Zero)
{
graphics.ReleaseHdc(hdc);
}
}
}
从Paint事件处理程序或其他具有Graphics实例的适当上下文中调用DrawRegion()方法,例如在示例中绘制到Image对象中.
显然,你可以使这个扩展方法更方便.另外,虽然在这个例子中我直接处理句柄的初始化和释放,但是更好的实现会将句柄包装在适当的SafeHandle子类中,这样你就可以方便地使用而不是try / finally,并获得备份完成(如果您忘记处置).