TextInputLayout源码解析

1. draw()

               
       @Override
       public void draw(Canvas canvas) {
           super.draw(canvas);
           if (mHintEnabled) {
               mCollapsingTextHelper.draw(canvas);
           }
       }

   mHintEnabled默认为true:

                
    mHintEnabled = a.getBoolean(R.styleable.TextInputLayout_hintEnabled, true);

2. onLayout()

               
       @Override
       protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
           super.onLayout(changed, left, top, right, bottom);
           if (mHintEnabled && mEditText != null) {
               final int l = mEditText.getLeft() + mEditText.getCompoundPaddingLeft();
               final int r = mEditText.getRight() - mEditText.getCompoundPaddingRight();
               mCollapsingTextHelper.setExpandedBounds(l,
                       mEditText.getTop() + mEditText.getCompoundPaddingTop(),
                       r, mEditText.getBottom() - mEditText.getCompoundPaddingBottom());
               // Set the collapsed bounds to be the the full height (minus padding) to match the
               // EditText's editable area
               mCollapsingTextHelper.setCollapsedBounds(l, getPaddingTop(),
                       r, bottom - top - getPaddingBottom());
               mCollapsingTextHelper.recalculate();
           }
       }

         
    private void setEditText(EditText editText) {
        // If we already have an EditText, throw an exception
        if (mEditText != null) {
            throw new IllegalArgumentException("We already have an EditText, can only have one");
        }
        if (!(editText instanceof TextInputEditText)) {
            Log.i(LOG_TAG, "EditText added is not a TextInputEditText. Please switch to using that"
                    + " class instead.");
        }
        mEditText = editText;
        // Use the EditText's typeface, and it's text size for our expanded text
        mCollapsingTextHelper.setTypefaces(mEditText.getTypeface());
        mCollapsingTextHelper.setExpandedTextSize(mEditText.getTextSize());
        final int editTextGravity = mEditText.getGravity();
        mCollapsingTextHelper.setCollapsedTextGravity(
                Gravity.TOP | (editTextGravity & GravityCompat.RELATIVE_HORIZONTAL_GRAVITY_MASK));
        mCollapsingTextHelper.setExpandedTextGravity(editTextGravity);
        // Add a TextWatcher so that we know when the text input has changed
        mEditText.addTextChangedListener(new TextWatcher() {
            @Override
            public void afterTextChanged(Editable s) {
                updateLabelState(true);
                if (mCounterEnabled) {
                    updateCounter(s.length());
                }
            }
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {}
        });
        // Use the EditText's hint colors if we don't have one set
        if (mDefaultTextColor == null) {
            mDefaultTextColor = mEditText.getHintTextColors();
        }
        // If we do not have a valid hint, try and retrieve it from the EditText, if enabled
        if (mHintEnabled && TextUtils.isEmpty(mHint)) {
            setHint(mEditText.getHint());
            // Clear the EditText's hint as we will display it ourselves
            mEditText.setHint(null);
        }
        if (mCounterView != null) {
            updateCounter(mEditText.getText().length());
        }
        if (mIndicatorArea != null) {
            adjustIndicatorPadding();
        }
        // Update the label visibility with no animation
        updateLabelState(false);
    }

• 该方法里主要处理
• 监听EditText输入:在监听回调中,可以获取到EditText输入文本的长度,并且展示

              
      private void updateCounter(int length) {
          boolean wasCounterOverflowed = mCounterOverflowed;
          if (mCounterMaxLength == INVALID_MAX_LENGTH) {
              mCounterView.setText(String.valueOf(length));
              mCounterOverflowed = false;
          } else {
              mCounterOverflowed = length > mCounterMaxLength;
              if (wasCounterOverflowed != mCounterOverflowed) {
                  mCounterView.setTextAppearance(getContext(), mCounterOverflowed ?
                          mCounterOverflowTextAppearance : mCounterTextAppearance);
              }
              mCounterView.setText(getContext().getString(R.string.character_counter_pattern,
                      length, mCounterMaxLength));
          }
          if (mEditText != null && wasCounterOverflowed != mCounterOverflowed) {
              updateLabelState(false);
              updateEditTextBackground();
          }
      }

• EidtText控件中hint隐藏文字在获取到焦点的时候,所做的网上动画效果:调用的方法就是updateLabelState()

              
      private void updateLabelState(boolean animate) {
          final boolean hasText = mEditText != null && !TextUtils.isEmpty(mEditText.getText());//EditText文本是否为空
          final boolean isFocused = arrayContains(getDrawableState(), android.R.attr.state_focused);//EditText是否获取到焦点
          final boolean isErrorShowing = !TextUtils.isEmpty(getError());
          if (mDefaultTextColor != null) {
              mCollapsingTextHelper.setExpandedTextColor(mDefaultTextColor.getDefaultColor());
          }
          if (mCounterOverflowed && mCounterView != null) {
              mCollapsingTextHelper.setCollapsedTextColor(mCounterView.getCurrentTextColor());
          } else if (isFocused && mFocusedTextColor != null) {
              mCollapsingTextHelper.setCollapsedTextColor(mFocusedTextColor.getDefaultColor());
          } else if (mDefaultTextColor != null) {
              mCollapsingTextHelper.setCollapsedTextColor(mDefaultTextColor.getDefaultColor());
          }
          if (hasText || isFocused || isErrorShowing) {
              // We should be showing the label so do so if it isn't already
              collapseHint(animate);
          } else {
              // We should not be showing the label so hide it
              expandHint(animate);
          }
      }

  动画

               
     //关闭动画,如果有正在运行的动画,先关闭在开启
     private void collapseHint(boolean animate) {
          if (mAnimator != null && mAnimator.isRunning()) {
              mAnimator.cancel();
          }
          if (animate && mHintAnimationEnabled) {
              animateToExpansionFraction(1f);
          } else {
              mCollapsingTextHelper.setExpansionFraction(1f);
          }
      }
      private void expandHint(boolean animate) {
          if (mAnimator != null && mAnimator.isRunning()) {
              mAnimator.cancel();
          }
          if (animate && mHintAnimationEnabled) {
              animateToExpansionFraction(0f);
          } else {
              mCollapsingTextHelper.setExpansionFraction(0f);
          }
      }

                
      private void animateToExpansionFraction(final float target) {
          if (mCollapsingTextHelper.getExpansionFraction() == target) {
              return;
          }
          if (mAnimator == null) {
              mAnimator = ViewUtils.createAnimator();
              mAnimator.setInterpolator(AnimationUtils.LINEAR_INTERPOLATOR);
              mAnimator.setDuration(ANIMATION_DURATION);
              //动画监听
              mAnimator.setUpdateListener(new ValueAnimatorCompat.AnimatorUpdateListener() {
                  @Override
                  public void onAnimationUpdate(ValueAnimatorCompat animator) {
                      mCollapsingTextHelper.setExpansionFraction(animator.getAnimatedFloatValue());//最后交给了CollapsingTextHelp类去处理
                  }
              });
          }
          mAnimator.setFloatValues(mCollapsingTextHelper.getExpansionFraction(), target);
          mAnimator.start();//开启动画
      }

• CollapsingTextHelp类就是TextInputLayout的辅助类,主要用于展示EditText提示信息,和动画处理

           
 //作为TextInputLayout的全局变量
private final CollapsingTextHelper mCollapsingTextHelper = new CollapsingTextHelper(this);