Question

我希望在屏幕中央显示为7 x 7方格，但是正如您在当前代码中看到的那样，垂直线位于正确的位置，而水平线则不是。我相信这是一个简单的解决方案，任何帮助将不胜感激 -

public class GameGrid extends View {

    Paint black = new Paint();

    public GameGrid(Context context) {
        super(context);

        black.setColor(Color.BLACK);
        black.setStrokeWidth(8);
    }

    @Override
    public void onDraw(Canvas canvas) {

        float startX;
        float stopX;
        float startY;
        float stopY;

        int width = canvas.getWidth();
        int height = canvas.getHeight();

        int gridSize = 7;
        int gridSpacing = width / gridSize;

        //Vertical Grid-lines
        for (int i = 0; i < gridSize; i++) {

            startX = width / 2 - height / 2;
            stopX = width / 2 + height / 2;

            startY = i*gridSpacing;
            stopY = i*gridSpacing;

            canvas.drawLine(startX, startY, stopX, stopY, black);

        }

        //Horizontal Grid-lines
        for (int i = 0; i < gridSize; i++) {

            startX = i*gridSpacing;
            stopX = i*gridSpacing;

            startY = height / 2 - width / 2;
            stopY = height / 2 + width / 2;

            canvas.drawLine(startX, startY, stopX, stopY, black);
        }
    }

Picture of what grid currently looks like

Answer 1

您缺少偏移（在两个轴上）。为什么不预先计算xOffset和yOffset以及根据(xOffset, yOffset)点开始绘画？

类似的东西：

@Override
public void onDraw(Canvas canvas) {

    float startX;
    float stopX;
    float startY;
    float stopY;

    int width = canvas.getWidth();
    int height = canvas.getHeight();

    int gridSize = 7;
    int gridSpacing = Math.min(width, height) / gridSize;
    int boardSize = gridSize * gridSpacing;

    int xOffset = (width - boardSize)/2;
    int yOffset = (height - boardSize)/2; 

    //Vertical Grid-lines
    for (int i = 0; i < gridSize; i++) {

        startX = xOffset + i*gridSpacing;
        startY = yOffset;

        stopX = startX;
        stopY = startY + boardSize;

        canvas.drawLine(startX, startY, stopX, stopY, black);

    }

    //Horizontal Grid-lines
    for (int i = 0; i < gridSize; i++) {

        startX = xOffset;
        startY = yOffset + i*gridSpacing;

        stopX = startX + boardSize;
        stopY = startY;

        canvas.drawLine(startX, startY, stopX, stopY, black);
    }
}

如果您想确保始终居中（例如在风景中），您应该设置：

int gridSpacing = Math.min(width, height) / gridSize;

Answer 2

我是GUESS问题是画布不是正方形的吗？高度大于宽度。

因此在垂直网格线中

startX = width / 2 - height / 2;

给出一个负数，并将起点放在屏幕左侧。它看起来很好，但长度是错误的。

对于水平网格线

 startY = height / 2 - width / 2;

是一个正数，你从屏幕中间开始。同样，endY值超过一定量（注意水平网格线比垂直网格线长，并向下偏移）

也许试试

//Horizontal Y vals
startY = 0;
stopY   = height;

无法为Android游戏绘制方格

2 个答案: