TextDrawerImpl.java

package com.espian.showcaseview.drawing;

import com.espian.showcaseview.ShowcaseView;
import com.espian.showcaseview.utils.ShowcaseAreaCalculator;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.text.DynamicLayout;
import android.text.Layout;
import android.text.SpannableString;
import android.text.TextPaint;
import android.text.TextUtils;
import android.text.style.TextAppearanceSpan;

/**
 * Draws the text as required by the ShowcaseView
 */
public class TextDrawerImpl implements TextDrawer {

	private static final int PADDING = 24;
	private static final int ACTIONBAR_PADDING = 66;

	private final TextPaint mPaintTitle;
	private final TextPaint mPaintDetail;

	private CharSequence mTitle, mDetails;
	private float mDensityScale;
	private ShowcaseAreaCalculator mCalculator;
	private float[] mBestTextPosition = new float[3];
	private DynamicLayout mDynamicTitleLayout;
	private DynamicLayout mDynamicDetailLayout;
	private TextAppearanceSpan mTitleSpan;
	private TextAppearanceSpan mDetailSpan;

	public TextDrawerImpl(float densityScale, ShowcaseAreaCalculator calculator) {
		mDensityScale = densityScale;
		mCalculator = calculator;

		mPaintTitle = new TextPaint();
		mPaintTitle.setAntiAlias(true);

		mPaintDetail = new TextPaint();
		mPaintDetail.setAntiAlias(true);
	}

	@Override
	public void draw(Canvas canvas, boolean hasPositionChanged) {
		if (shouldDrawText()) {
			float[] textPosition = getBestTextPosition();

			if (!TextUtils.isEmpty(mTitle)) {
				canvas.save();
				if (hasPositionChanged) {
					mDynamicTitleLayout = new DynamicLayout(mTitle, mPaintTitle,
							(int) textPosition[2], Layout.Alignment.ALIGN_NORMAL,
							1.0f, 1.0f, true);
				}
				canvas.translate(textPosition[0], textPosition[1]);
				mDynamicTitleLayout.draw(canvas);
				canvas.restore();
			}

			if (!TextUtils.isEmpty(mDetails)) {
				canvas.save();
				if (hasPositionChanged) {
					mDynamicDetailLayout = new DynamicLayout(mDetails, mPaintDetail,
							(int) textPosition[2],
							Layout.Alignment.ALIGN_NORMAL,
							1.2f, 1.0f, true);
				}
				canvas.translate(textPosition[0], textPosition[1] + mDynamicTitleLayout.getHeight());
				mDynamicDetailLayout.draw(canvas);
				canvas.restore();

			}
		}
	}

	@Override
	public void setDetails(CharSequence details) {
		if (details != null) {
			SpannableString ssbDetail = new SpannableString(details);
			ssbDetail.setSpan(mDetailSpan, 0, ssbDetail.length(), 0);
			mDetails = ssbDetail;
		}
	}

	@Override
	public void setTitle(CharSequence title) {
		if (title != null) {
			SpannableString ssbTitle = new SpannableString(title);
			ssbTitle.setSpan(mTitleSpan, 0, ssbTitle.length(), 0);
			mTitle = ssbTitle;
		}
	}

	/**
	 * Calculates the best place to position text
	 *
	 * @param canvasW width of the screen
	 * @param canvasH height of the screen
	 */
	 @Override
	 public void calculateTextPosition(int canvasW, int canvasH, ShowcaseView showcaseView) {

		Rect showcase = showcaseView.hasShowcaseView() ?
				mCalculator.getShowcaseRect() :
					new Rect();

				int[] areas = new int[4]; //left, top, right, bottom
				areas[0] = showcase.left * canvasH;
				areas[1] = showcase.top * canvasW;
				areas[2] = (canvasW - showcase.right) * canvasH;
				areas[3] = (canvasH - showcase.bottom) * canvasW;

				int largest = 0;
				for(int i = 1; i < areas.length; i++) {
					if(areas[i] > areas[largest])
						largest = i;
				}

				// Position text in largest area
				switch(largest) {
				case 0:
					mBestTextPosition[0] = PADDING * mDensityScale;
					mBestTextPosition[1] = PADDING * mDensityScale;
					mBestTextPosition[2] = showcase.left - 2 * PADDING * mDensityScale;
					break;
				case 1:
					mBestTextPosition[0] = PADDING * mDensityScale;
					mBestTextPosition[1] = (PADDING + ACTIONBAR_PADDING) * mDensityScale;
					mBestTextPosition[2] = canvasW - 2 * PADDING * mDensityScale;
					break;
				case 2:
					mBestTextPosition[0] = showcase.right + PADDING * mDensityScale;
					mBestTextPosition[1] = PADDING * mDensityScale;
					mBestTextPosition[2] = (canvasW - showcase.right) - 2 * PADDING * mDensityScale;
					break;
				case 3:
					mBestTextPosition[0] = PADDING * mDensityScale;
					mBestTextPosition[1] = showcase.bottom + PADDING * mDensityScale;
					mBestTextPosition[2] = canvasW - 2 * PADDING * mDensityScale;
					break;
				}
				if(showcaseView.getConfigOptions().centerText) {
					// Center text vertically or horizontally
					switch(largest) {
					case 0:
					case 2:
						mBestTextPosition[1] += canvasH / 4;
						break;
					case 1:
					case 3:
						mBestTextPosition[2] /= 2;
						mBestTextPosition[0] += canvasW / 4;
						break;
					} 
				} else {
					// As text is not centered add actionbar padding if the text is left or right
					switch(largest) {
					case 0:
					case 2:
						mBestTextPosition[1] += ACTIONBAR_PADDING * mDensityScale;
						break;
					}
				}
	 }

	 @Override
	 public void setTitleStyling(Context context, int styleId) {
		 mTitleSpan = new TextAppearanceSpan(context, styleId);
	 }

	 @Override
	 public void setDetailStyling(Context context, int styleId) {
		 mDetailSpan = new TextAppearanceSpan(context, styleId);
	 }

	 public float[] getBestTextPosition() {
		 return mBestTextPosition;
	 }

	 public boolean shouldDrawText() {
		 return !TextUtils.isEmpty(mTitle) || !TextUtils.isEmpty(mDetails);
	 }
}