Android Open Source - GuiLib Floating Hint Edit Text

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Back to project page GuiLib.
License

The source code is released under:
Apache License
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Java Source Code

package com.thebnich.floatinghintedittext;
//from  w w  w.java2s .c  o  m
import android.content.Context;
import android.content.res.ColorStateList;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.widget.EditText;

import com.gandulf.guilib.R;

public class FloatingHintEditText extends EditText {
  private static enum Animation {
    NONE, SHRINK, GROW
  }

  private final Paint mFloatingHintPaint = new Paint();
  private final ColorStateList mHintColors;

  private int mHintSize;
  private final int mAnimationSteps;

  private boolean mWasEmpty;
  private int mAnimationFrame;
  private Animation mAnimation = Animation.NONE;

  public FloatingHintEditText(Context context) {
    this(context, null);
  }

  public FloatingHintEditText(Context context, AttributeSet attrs) {
    this(context, attrs, R.attr.floatingHintEditTextStyle);
  }

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

    mHintSize = getResources().getDimensionPixelSize(R.dimen.floatinghintedittext_hint_size);

    mAnimationSteps = getResources().getInteger(R.dimen.floatinghintedittext_animation_steps);

    mHintColors = getHintTextColors();
    mWasEmpty = TextUtils.isEmpty(getText());
  }

  @Override
  public int getCompoundPaddingTop() {
    return super.getCompoundPaddingTop() + mHintSize;
  }

  @Override
  protected void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter) {
    super.onTextChanged(text, start, lengthBefore, lengthAfter);

    final boolean isEmpty = TextUtils.isEmpty(getText());

    // The empty state hasn't changed, so the hint stays the same.
    if (mWasEmpty == isEmpty) {
      return;
    }

    mWasEmpty = isEmpty;

    // Don't animate if we aren't visible.
    if (!isShown()) {
      return;
    }

    if (isEmpty) {
      mAnimation = Animation.GROW;
      setHintTextColor(Color.TRANSPARENT);
    } else {
      mAnimation = Animation.SHRINK;
    }
  }

  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    if (TextUtils.isEmpty(getHint())) {
      return;
    }

    final boolean isAnimating = mAnimation != Animation.NONE;

    // The large hint is drawn by Android, so do nothing.
    if (!isAnimating && TextUtils.isEmpty(getText())) {
      return;
    }

    mFloatingHintPaint.set(getPaint());
    mFloatingHintPaint.setColor(mHintColors.getColorForState(getDrawableState(), mHintColors.getDefaultColor()));

    final float hintPosX = getCompoundPaddingLeft() + getScrollX();
    final float normalHintPosY = getBaseline();
    final float floatingHintPosY = normalHintPosY + getPaint().getFontMetricsInt().top + getScrollY();
    final float normalHintSize = getTextSize();

    // If we're not animating, we're showing the floating hint, so draw it and bail.
    if (!isAnimating) {
      mFloatingHintPaint.setTextSize(mHintSize);
      canvas.drawText(getHint().toString(), hintPosX, floatingHintPosY, mFloatingHintPaint);
      return;
    }

    if (mAnimation == Animation.SHRINK) {
      drawAnimationFrame(canvas, normalHintSize, mHintSize, hintPosX, normalHintPosY, floatingHintPosY);
    } else {
      drawAnimationFrame(canvas, mHintSize, normalHintSize, hintPosX, floatingHintPosY, normalHintPosY);
    }

    mAnimationFrame++;

    if (mAnimationFrame == mAnimationSteps) {
      if (mAnimation == Animation.GROW) {
        setHintTextColor(mHintColors);
      }
      mAnimation = Animation.NONE;
      mAnimationFrame = 0;
    }

    invalidate();
  }

  private void drawAnimationFrame(Canvas canvas, float fromSize, float toSize, float hintPosX, float fromY, float toY) {
    final float textSize = lerp(fromSize, toSize);
    final float hintPosY = lerp(fromY, toY);
    mFloatingHintPaint.setTextSize(textSize);
    canvas.drawText(getHint().toString(), hintPosX, hintPosY, mFloatingHintPaint);
  }

  private float lerp(float from, float to) {
    final float alpha = (float) mAnimationFrame / (mAnimationSteps - 1);
    return from * (1 - alpha) + to * alpha;
  }
}
Java Source Code List
