Picturebox:更新时内容消失

问题描述

你好，

我编写了一个简单的程序，以通过条形图显示街道外观的数量.但是当我画新的时，旧的就消失了.

Hi there,

i make a simple program to display the number of street''s appearances through bar chart. but when i draw new one, the old one disappear.

void PicStreetPaint(object sender, PaintEventArgs e)
{
    if(bClear){
        e.Graphics.Clear(Color.White);
    }
    else{
        // s = street-th, r = height of bar
        Brush bColor = new SolidBrush(Color.FromName(aColor[s]));
        grStreet.FillRectangle(bColor, s * 30, 0, 30, r * 20);
    }
}

这是旧代码，当我移动表格时，内容消失了，因为它没有重绘.

this is old code, when it i move form around, contents disappear because it not redraw.

public void UpdateStreet(int number)
{
    if(number == 0){
        return;
    }
    int[] Street = new int[] {1,1,1,2,2,2,3,3,3,4,4,4,
                            5,5,5,6,6,6,7,7,7,8,8,8,
                            9,9,9,10,10,10,11,11,11,12,12,12};
    string[] aColor = new string[]{"Silver", "Tomato", "Red", "Yellow", "GreenYellow", "Green", "Teal", "DodgerBlue", "SlateBlue", "Indigo", "Crimson", "Plum"};
    int r = 0, s = 0;
    Graphics grStreet = picStreet.CreateGraphics();
    Brush bColor;
    number -= 1; // adjust to array
    s = Street[number] - 1; // get street-th
    bColor = new SolidBrush(Color.FromName(aColor[s]));
    street[s] += 1; // update the number of street's appearance
    r = street[s]; // height of bar = number of street's appearance
    grStreet.FillRectangle(bColor, s * 30, 0, 30, r * 20);
    picStreet.Update();
}

非常感谢.

thank you very much.

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