Question

嗨，我正在做一个练习项目，可以用我放置的坐标绘制一条线。屏幕只需要文本字段和一个按钮。例如，如果我在这两个文本字段中放入“20”和“30”并单击“绘制”按钮，我希望应用程序在另一个视图中从（0,0）到（20,30）绘制一条线。

我已经知道如何使用“onDraw（）”绘制一条线，但我不知道将这两个参数传递给onDraw（）函数。另外，每次单击绘图按钮或只在一个视图中更改onDraw（）函数时，我应该创建一个新视图吗？

感谢!!!!!!!

Answer 1

所以你要做的就是让视图不必担心彼此。你有一个处理绘制线的视图，两个处理输入的EditText视图，例如，提供坐标的按钮。假设您有一个包含这些视图的布局，这里是一个简单的自定义视图示例，您可以使用它来绘制该行：

public class LineView extends View {
    /**
     * Container to hold the x1, y1, x2, y2 values, respectively
     */
    private float[] mCoordinates;

    /**
     * The paint with which the line will be drawn
     */
    private Paint mLinePaint = new Paint(Paint.ANTI_ALIAS_FLAG);

    public LineView (Context context) {
        super(context);
    }

    public LineView (Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public LineView (Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    /**
     * Set the color with which the line should be drawn
     * @param color the color to draw the line with
     */
    public void setLineColor (int color) {
        mLinePaint.setColor(color);
        invalidate();
    }

    /**
     * Set the coordinates of the line to be drawn. The origin (0, 0) is the
     * top left of the View.
     * @param x1 the starting x coordinate
     * @param y1 the starting y coordinate
     * @param x2 the ending x coordinate
     * @param y2 the ending y coordinate
     */
    public void setCoordinates (float x1, float y1, float x2, float y2) {
        ensureCoordinates();

        mCoordinates[0] = x1;
        mCoordinates[1] = y1;
        mCoordinates[2] = x2;
        mCoordinates[3] = y2;

        invalidate();
    }

    private void ensureCoordinates () {
        if (mCoordinates == null) {
            mCoordinates = new float[4];
        }
    }

    @Override
    protected void onDraw (Canvas canvas) {
        if (mCoordinates != null) {
            canvas.drawLine(
                    mCoordinates[0],
                    mCoordinates[1],
                    mCoordinates[2],
                    mCoordinates[3],
                    mLinePaint
            );
        }
    }
}

除了一个简单的例子，给出上面关于你的布局的假设，你可以如何实现它。

public class EditTextActivity extends Activity implements View.OnClickListener {
    private EditText mInputX;
    private EditText mInputY;
    private Button mDrawButton;
    private LineView mLineView;

    public void onCreate (Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.my_layout);

        mInputX = (EditText) findViewById(R.id.input_x);
        mInputY = (EditText) findViewById(R.id.input_y);
        mDrawButton = (Button) findViewById(R.id.draw_button);

        mLineView = (LineView) findViewById(R.id.line_view);
        mLineView.setColor(Color.GREEN);

        mDrawButton.setOnClickListener(this);
    }

    @Override
    public void onClick (View v) {
        final float x1 = 0;
        final float y1 = 0;
        final float x2 = getValue(mInputX);
        final float y2 = getValue(mInputY);

        mLineView.setCoordinates(x1, y1, x2, y2);
    }

    private static float getValue (EditText text) {
        try {
            return Float.parseFloat(text.getText().toString());
        } catch (NumberFormatException ex) {
            return 0;
        }
    }
}

Answer 2

Here是您问题的答案。要获得EditText的值，您只需在DrawView方法 -

中执行此操作即可

public String value;
public int value_int;//This variable should be defined global
EditText text=(EditText)context.findViewById(ID);
value=text.getEditableText().toString();
value_int=Integer.parseInt(value);

在value_int方法中替换此canvas.DrawLine(..)。

Android-如何使用特定参数绘制可更改的行？

2 个答案: