c#使用gdi32.dll和System.Drawing.Graphics绘图
作者：互联网
所以我有一些代码在gdi32.dll的图片框顶部创建一个高亮效果,我想知道是否有更简单的方法来使用System.Drawing.Graphics？基本上使用gdi32.dll,我必须在绘制后捕获屏幕截图,将其发布到我的图片框然后我能够绘制更多的东西并更改我使用的笔的颜色.如果我只是尝试更改笔的粗细和颜色并再次在屏幕上绘图,如果我改变了已经绘制的内容.
现在我有一个版本,使用System.Drawing.Graphics和FillPolygon的大量数学,但如果我画了一个我已经画过的区域,它只会让我画的区域更暗.只要你还没有使用鼠标遮住区域,它就不能用gdi32.dll进行justr阴影处理.有什么建议？
public partial class Form9 : Form
{
private bool is_mouse_down { get; set; } // Will check if the mouse is down or not.
private Color Pen_Color = new Color();
private int Pen_Type { get; set; }
private int Thickness { get; set; }
private bool Start { get; set; }
List<Point> Points = new List<Point>();
public Form9()
{
InitializeComponent();
pictureBox1.Dock = DockStyle.Fill;
Pen_Color = Color.Blue;
Pen_Type = 13; // Type = 9 for highlighter, Type = 13 for solid.
Thickness = 2;
Start = false;
pictureBox1.MouseDown += pictureBox1_MouseDown;
pictureBox1.MouseUp += pictureBox1_MouseUp;
pictureBox1.MouseMove += pictureBox1_MouseMove;
pictureBox1.Paint += pictureBox1_OnPaint;
}
private void DrawHighlight(Graphics g, Point[] usePoints, int brushSize, int penType, Color brushColor)
{
int useColor = System.Drawing.ColorTranslator.ToWin32(brushColor);
IntPtr pen = GetImage.GDI32.CreatePen(GetImage.GDI32.PS_SOLID, brushSize, (uint)useColor);
IntPtr hDC = g.GetHdc();
IntPtr xDC = GetImage.GDI32.SelectObject(hDC, pen);
GetImage.GDI32.SetROP2(hDC, penType);//GetImage.GDI32.R2_MASKPEN);
for (int i = 1; i <= usePoints.Length - 1; i++)
{
Point p1 = usePoints[i - 1];
Point p2 = usePoints[i];
GetImage.GDI32.MoveToEx(hDC, p1.X, p1.Y, IntPtr.Zero);
GetImage.GDI32.LineTo(hDC, p2.X, p2.Y);
}
GetImage.GDI32.SetROP2(hDC, GetImage.GDI32.R2_COPYPEN);
GetImage.GDI32.SelectObject(hDC, xDC);
GetImage.GDI32.DeleteObject(pen);
g.ReleaseHdc(hDC);
}
private void pictureBox1_OnPaint(object sender, PaintEventArgs e)
{
if (Start)
{
base.OnPaint(e);
if (is_mouse_down)
{
DrawHighlight(e.Graphics, Points.ToArray(), Thickness, Pen_Type, Pen_Color);
}
}
}
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
Points.Clear();
Start = true;
is_mouse_down = true;
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
is_mouse_down = false;
using (Image img = CaptureScreen())
{
try
{
if (System.IO.File.Exists(Program.ProgramPath + @"\Temp\marked.bmp"))
{
System.IO.File.Delete(Program.ProgramPath + @"\Temp\marked.bmp");
}
}
catch (Exception Ex)
{
MessageBox.Show("File Delete Error" + Environment.NewLine + Convert.ToString(Ex));
}
try
{
img.Save(Program.ProgramPath + @"\Temp\marked.bmp", System.Drawing.Imaging.ImageFormat.Bmp);
}
catch (Exception Ex)
{
MessageBox.Show("Unable to save Screenshot" + Environment.NewLine + Convert.ToString(Ex));
}
}
if (System.IO.File.Exists(Program.ProgramPath + @"\Temp\marked.bmp"))
{
using (FileStream fs = new System.IO.FileStream(Program.ProgramPath + @"\Temp\marked.bmp", System.IO.FileMode.Open, System.IO.FileAccess.Read, FileShare.Read))
{
pictureBox1.Image = Image.FromStream(fs);
}
}
pictureBox1.Invalidate(); // Refreshes picturebox image.
}
public Image CaptureScreen()
{
GetImage gi = new GetImage();
return gi.CaptureWindow(GetImage.User32.GetDesktopWindow());
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (is_mouse_down == true) // Check to see if the mouse button is down while moving over the form.
{
Points.Add(new Point(e.X, e.Y));
pictureBox1.Invalidate(); // Refreshes picturebox image.
}
}
这是我正在谈论的几张照片：
使用System.Drawing.Graphics：
使用gdi32.dll：
UPDATE
在测试了一些代码后……我得到了一些奇怪的东西.
解决方法:
这是一种绘制半透明颜色的多个独立笔划而不会堆积alpha的方法：
它使用两个列表,一个用于笔划,一个用于当前笔划：
List<List<Point>> strokes = new List<List<Point>>();
List<Point> currentStroke = new List<Point>();
它们以通常的方式填充
private void canvas_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button.HasFlag(MouseButtons.Left))
{
currentStroke.Add(e.Location);
if (currentStroke.Count == 1)
currentStroke.Add(new Point(currentStroke[0].X + 1,
currentStroke[0].Y));
canvasInvalidate();
}
}
private void canvas_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button.HasFlag(MouseButtons.Left))
{
currentStroke.Add(e.Location);
canvas.Invalidate();
}
}
private void canvas_MouseUp(object sender, MouseEventArgs e)
{
if (currentStroke.Count > 1)
{
strokes.Add(currentStroke.ToList());
currentStroke.Clear();
}
canvas.Invalidate();
}
在此版本中,我们通过仅在一次调用中绘制所有像素来避免重叠笔划的叠加效果.通过从笔划创建GraphicsPath并填充它来绘制所有像素：
private void canvas_Paint(object sender, PaintEventArgs e)
{
if (strokes.Count > 0 || currentStroke.Count > 0)
{
GraphicsPath gp = new GraphicsPath();
gp.FillMode = FillMode.Winding;
if (currentStroke.Count > 0)
{
gp.AddCurve(currentStroke.ToArray());
gp.CloseFigure();
}
foreach (var stroke in strokes)
{
gp.AddCurve(stroke.ToArray());
gp.CloseFigure();
}
using (SolidBrush b = new SolidBrush(Color.FromArgb(77, 177, 99, 22)))
{
e.Graphics.FillPath(b, gp);
}
}
}
请注意,在绘制时应注意不要移回当前笔划,否则弯曲的路径部分会产生孔洞！
清除或保存按钮很简单,前者清除两个列表并使其无效,后者将使用DrawToBitmap来保存控件.
注意：为了避免闪烁07.02,canval面板是DoubleBuffered！
更新：
这是使用Pen绘制叠加层的另一种方法.为了避免堆积alpha和更改的颜色值(取决于PixelFormat),它使用快速功能修改覆盖中的所有设置像素以具有相同的覆盖颜色：
笔划集合代码是相同的. Paint缩减为调用函数来创建叠加位图并绘制它：
private void canvas_Paint(object sender, PaintEventArgs e)
{
using (Bitmap bmp = new Bitmap(canvas.ClientSize.Width,
canvas.ClientSize.Height, PixelFormat.Format32bppPArgb))
{
PaintToBitmap(bmp);
e.Graphics.DrawImage(bmp, 0, 0);
}
第一个函数完成绘图,与之前非常相似,但使用简单的笔划：
private void PaintToBitmap(Bitmap bmp)
{
Color overlayColor = Color.FromArgb(77, 22, 99, 99);
using (Graphics g = Graphics.FromImage(bmp))
using (Pen p = new Pen(overlayColor, 15f))
{
p.MiterLimit = p.Width / 2;
p.EndCap = LineCap.Round;
p.StartCap = LineCap.Round;
p.LineJoin = LineJoin.Round;
g.SmoothingMode = SmoothingMode.AntiAlias;
if (currentStroke.Count > 0)
{
g.DrawCurve(p, currentStroke.ToArray());
}
foreach (var stroke in strokes)
g.DrawCurve(p, stroke.ToArray());
}
SetAlphaOverlay(bmp, overlayColor);
}
它还调用将所有设置像素“展平”为叠加颜色的函数：
void SetAlphaOverlay(Bitmap bmp, Color col)
{
Size s = bmp.Size;
PixelFormat fmt = bmp.PixelFormat;
Rectangle rect = new Rectangle(Point.Empty, s);
BitmapData bmpData = bmp.LockBits(rect, ImageLockMode.ReadOnly, fmt);
int size1 = bmpData.Stride * bmpData.Height;
byte[] data = new byte[size1];
System.Runtime.InteropServices.Marshal.Copy(bmpData.Scan0, data, 0, size1);
for (int y = 0; y < s.Height; y++)
{
for (int x = 0; x < s.Width; x++)
{
int index = y * bmpData.Stride + x * 4;
if (data[index + 0] + data[index + 1] + data[index + 2] > 0)
{
data[index + 0] = col.B;
data[index + 1] = col.G;
data[index + 2] = col.R;
data[index + 3] = col.A;
}
}
}
System.Runtime.InteropServices.Marshal.Copy(data, 0, bmpData.Scan0, data.Length);
bmp.UnlockBits(bmpData);
}
它使用LockBits,所以速度非常快..
这是在行动：
更新2：
只是为了它的乐趣,这里只有几行的扩展,增加了绘制填充曲线的选项：
填充模式通过使第一个元素两次存储在廉价黑客中.这些是变化：
在MouseDown中：
currentStroke.Add(e.Location);
if (cbx_Fill.Checked)
currentStroke.Add(e.Location);
在PaintToBitmap中：
g.SmoothingMode = SmoothingMode.AntiAlias;
if (currentStroke.Count > 0)
{
if (cbx_Fill.Checked)
g.FillClosedCurve(b, currentStroke.ToArray());
else
g.DrawCurve(p, currentStroke.ToArray());
}
foreach (var stroke in strokes)
if (stroke[0]==stroke[1])
g.FillClosedCurve(b, stroke.ToArray());
else
g.DrawCurve(p, stroke.ToArray());
还有一个演示：
标签：c,gdi-2,system-drawing,graphic 来源： https://codeday.me/bug/20190527/1163321.html