c# - C#图像处理非常慢

Question

在过去的几个月中，我一直在研究应用程序，它的功能之一就是可以裁剪图像。因此，我编写了一个函数，该函数绘制一个透明的橙色矩形，以向用户显示裁剪区域，但是它的工作速度非常慢-有人可以帮助我/向我展示一种使其更快的方法吗？

这是代码：

Image source;

private void pictureBox1_MouseDown(object sender, MouseEventArgs e) {
    mousePos = e.Location;
}

Point mousePos;

private void pictureBox1_MouseMove(object sender, MouseEventArgs e) {
    if (e.Button == MouseButtons.Left) {
        Image editSource = new Bitmap(source);
        Graphics g = Graphics.FromImage(editSource);
        SolidBrush brush = new SolidBrush(
            Color.FromArgb(128, Color.Orange.R, Color.Orange.G, Color.Orange.B));

        int width = e.X - mousePos.X;
        if (width < 0) {
            width *= -1;
        }

        int height = e.Y - mousePos.Y;
        if (height < 0) {
            height *= -1;
        }

        Size cropRectSize = new Size(width, height);
        Rectangle cropRect = new Rectangle(mousePos, cropRectSize);
        g.FillRectangle(brush, cropRect);
        pictureBox1.Image = editSource;
    }
}

Answer 1

因此，所有关于不使用图片框的建议...我会给你一种方法来做;）

其背后的想法是仅使用鼠标移动，鼠标向下移动等来存储应绘制的内容。然后在绘制时使用存储的状态。每当您在图片框上按下鼠标时，就会绘制一个橙色矩形（即使建议不要使用图片框，也可以将这种方法用于其他表面。）。

    Point startPoint;
    Point currentPoint;
    bool draw = false;
    private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
    {
        startPoint = e.Location;
        draw = true;
    }

    private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
    {
        draw = false;
    }

    private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
    {
        currentPoint = e.Location;
        pictureBox1.Invalidate();
    }

    private void pictureBox1_Paint(object sender, PaintEventArgs e)
    {
        if (draw)
        {
            int startX = Math.Min(startPoint.X, currentPoint.X);
            int startY = Math.Min(startPoint.Y, currentPoint.Y);
            int endX = Math.Max(startPoint.X, currentPoint.X);
            int endY = Math.Max(startPoint.Y, currentPoint.Y);
            e.Graphics.DrawRectangle(Pens.Orange, new Rectangle(startX, startY, endX-startX, endY-startY));
        }
    }