在编辑文本中绘制多行，例如记事本

Question

我正在查看 android SDK 中的记事本示例，请参阅此处： http://developer.android.com/resources/samples/NotePad/src/com/example/android/notepad/NoteEditor.html

事情是它只绘制光标所在的当前行，例如 http://cdn2.staztic.com/screenshots/simple-notepad-app-al-1。 jpg

但我想显示填满屏幕的线条，例如 http://www.itismyworld.info/wp-content/uploads/2010/03/AK-notebook.png

任何建议都会很棒。相关的代码似乎在这里：

    protected void onDraw(Canvas canvas) {

        // Gets the number of lines of text in the View.
        int count = getLineCount();

        // Gets the global Rect and Paint objects
        Rect r = mRect;
        Paint paint = mPaint;

        /*
         * Draws one line in the rectangle for every line of text in the EditText
         */
        for (int i = 0; i < count; i++) {

            // Gets the baseline coordinates for the current line of text
            int baseline = getLineBounds(i, r);

            /*
             * Draws a line in the background from the left of the rectangle to the right,
             * at a vertical position one dip below the baseline, using the "paint" object
             * for details.
             */
            canvas.drawLine(r.left, baseline + 1, r.right, baseline + 1, paint);
        }

        // Finishes up by calling the parent method
        super.onDraw(canvas);
    }

Answer 1

这是基于 jkhouws1 的代码建议和谷歌的笔记编辑器

public class LinedEditText extends EditText {
    private Rect mRect;
    private Paint mPaint;

    // we need this constructor for LayoutInflater
    public LinedEditText(Context context, AttributeSet attrs) {
        super(context, attrs);

        mRect = new Rect();
        mPaint = new Paint();
        mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
        mPaint.setColor(R.color.edit_note_line); //SET YOUR OWN COLOR HERE
    }

    @Override
    protected void onDraw(Canvas canvas) {
        //int count = getLineCount();

        int height = getHeight();
        int line_height = getLineHeight();

        int count = height / line_height;

        if (getLineCount() > count)
            count = getLineCount();//for long text with scrolling

        Rect r = mRect;
        Paint paint = mPaint;
        int baseline = getLineBounds(0, r);//first line

        for (int i = 0; i < count; i++) {

            canvas.drawLine(r.left, baseline + 1, r.right, baseline + 1, paint);
            baseline += getLineHeight();//next line
        }

        super.onDraw(canvas);
    }
}

在 Eclipse IDE 中按 Ctrl +Shift+O 添加所有需要的导入

Answer 2

我认为这就是你所需要的：

public class LinedEditText extends EditText {

    private static Paint linePaint;

    static {
        linePaint = new Paint();
        linePaint.setColor(Color.BLACK);
        linePaint.setStyle(Style.STROKE);
    }

    public LinedEditText(Context context, AttributeSet attributes) {
        super(context, attributes);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        Rect bounds = new Rect();
        int firstLineY = getLineBounds(0, bounds);
        int lineHeight = getLineHeight();
        int totalLines = Math.max(getLineCount(), getHeight() / lineHeight);

        for (int i = 0; i < totalLines; i++) {
            int lineY = firstLineY + i * lineHeight;
            canvas.drawLine(bounds.left, lineY, bounds.right, lineY, linePaint);
        }

        super.onDraw(canvas);
    }


}

Answer 3

也许在 for 循环之后，您会绘制估计的*额外的线。

getHeight() 将返回 EditText 的高度（以像素为单位）
getLineHeight() 将为一根标准线的高度

，因此 getHeight/getlineHeight-getCount 将是剩余要绘制的线数。

您不能使用 getLineBounds，使用上述函数您可以计算剩余要绘制的线的位置。

*估计是因为文本格式可能会改变行高，但由于这些行中还没有文本，所以这不应该成为问题。但出于同样的原因，您应该只绘制剩余的线条，而不是用它来绘制所有线条。

Answer 4

<com.example.goh2.pronoornotepad.LinedEditText
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="#ffffcc4b"
        android:gravity="top|left"
        android:singleLine="false"
        android:text=""
     />

上述 XML 与 Max4ever 的回答中的代码配合使用：

   public class LinedEditText extends EditText {
    private Rect mRect;
    private Paint mPaint;

// we need this constructor for LayoutInflater
   public LinedEditText(Context context, AttributeSet attrs) {
    super(context, attrs);

    mRect = new Rect();
    mPaint = new Paint();
    mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
    mPaint.setColor(R.color.edit_note_line); //SET YOUR OWN COLOR HERE
}

@Override
protected void onDraw(Canvas canvas) {
    //int count = getLineCount();

    int height = getHeight();
    int line_height = getLineHeight();

    int count = height / line_height;

    if (getLineCount() > count)
        count = getLineCount();//for long text with scrolling

    Rect r = mRect;
    Paint paint = mPaint;
    int baseline = getLineBounds(0, r);//first line

    for (int i = 0; i < count; i++) {

        canvas.drawLine(r.left, baseline + 1, r.right, baseline + 1, paint);
        baseline += getLineHeight();//next line
    }

    super.onDraw(canvas);
    }
 }