33.Android 自動適配字體大小的AutoAdjustSizeEditText

33.Android 自動適配字體大小的AutoAdjustSizeEditText

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AutoAdjustSizeEditText介紹

由於一個需求，就是一個定寬高的EditText裏，輸入後，要根據字的內容改變字體大小。

這時候就需要這麼一個自定適配字體大小的EditView。

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AutoAdjustSizeEditText原理

實現原理： 重寫EditText，覆寫其setText、onTextChanged和onSizeChanged方法。分別在這裏重新寫適配字體大小的邏輯處理，所謂的邏輯處理，就是計算單行可見文字的寬度，然後從自定義的最大字體開始嘗試，先用最大字體去寫字（ Paint.setTextSize(float textSize) ），然後判斷：最大字體畫出字的寬度>可見文字寬度。如果成立，那麼減小一號字體再去畫，不斷去減小字體去判斷，直到不成立時，就找到合適的字體大小了。

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AutoAdjustSizeEditText

public class AutoAdjustSizeEditText extends EditText {

    // 最小字體
    private static final float DEFAULT_MIN_TEXT_SIZE = 8.0f;
    // 最大字體
    private static final float DEFAULT_MAX_TEXT_SIZE = 16.0f;

    private Paint textPaint;
    private float minTextSize = DEFAULT_MIN_TEXT_SIZE;
    private float maxTextSize = DEFAULT_MAX_TEXT_SIZE;

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

    private void initialise() {
        DisplayMetrics displayMetrics = this.getResources().getDisplayMetrics();
        if (this.textPaint == null) {
            this.textPaint = new Paint();
            this.textPaint.set(this.getPaint());
        }
        this.maxTextSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, this.maxTextSize, displayMetrics);
        if (DEFAULT_MIN_TEXT_SIZE >= maxTextSize) {
            this.maxTextSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, this.maxTextSize, displayMetrics);
        }
        this.maxTextSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, this.maxTextSize, displayMetrics);
        this.minTextSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, this.minTextSize, displayMetrics);
    }

    /**
     * Re size the font so the specified text fits in the text box * assuming
     * the text box is the specified width.
     */
    private void fitText(String text, int textWidth) {
        if (textWidth > 0) {
            // 單行可見文字寬度
            int availableWidth = textWidth - this.getPaddingLeft() - this.getPaddingRight();
            float trySize = maxTextSize;
            // 先用最大字體寫字
            textPaint.setTextSize(trySize);
            // 如果最大字體>最小字體 && 最大字體畫出字的寬度>單行可見文字寬度
            while ((trySize > minTextSize) && (textPaint.measureText(text) > availableWidth)) {
                // 最大字體小一號
                trySize -= 1;
                // 保證大於最小字體
                if (trySize <= minTextSize) {
                    trySize = minTextSize;
                    break;
                }
                // 再次用新字體寫字
                textPaint.setTextSize(trySize);
            }
            this.setTextSize(trySize);
        }
    }


    /**
     * 重寫setText
     * 每次setText的時候
     *
     * @param text
     * @param type
     */
    @Override
    public void setText(CharSequence text, BufferType type) {
        this.initialise();
        String textString = text.toString();
        float trySize = maxTextSize;
        if (this.textPaint == null) {
            this.textPaint = new Paint();
            this.textPaint.set(this.getPaint());
        }
        this.textPaint.setTextSize(trySize);
        // 計算設置內容前 內容佔據的寬度
        int textWidth = (int) this.textPaint.measureText(textString);
        // 拿到寬度和內容，進行調整
        this.fitText(textString, textWidth);
        super.setText(text, type);
    }


    @Override
    protected void onTextChanged(CharSequence text, int start, int before, int after) {
        super.onTextChanged(text, start, before, after);
        this.fitText(text.toString(), this.getWidth());
    }


    /**
     * This is called during layout when the size of this view has changed. If
     * you were just added to the view hierarchy, you're called with the old
     * values of 0.
     *
     * @param w    Current width of this view.
     * @param h    Current height of this view.
     * @param oldw Old width of this view.
     * @param oldh Old height of this view.
     */
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        // 如果當前view的寬度 != 原來view的寬度
        if (w != oldw) this.fitText(this.getText().toString(), w);
    }


}

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AutoAdjustSizeEditTextActivity

AutoAdjustSizeEditTextActivity

public class AutoAdjustSizeEditTextActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentView(R.layout.activity_auto_adjust_size_edit_text);
    }
}

activity_auto_adjust_size_edit_text.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <camnter.newlife.widget.AutoAdjustSizeEditText
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:padding="16dp"
        android:text="Save you from anything"
        android:textColor="#ffFF4081" />

    <camnter.newlife.widget.AutoAdjustSizeEditText
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:padding="16dp"
        android:text="Save you from anything Save you from anything"
        android:textColor="#ffFF4081" />

    <camnter.newlife.widget.AutoAdjustSizeEditText
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:padding="16dp"
        android:text="Save you from anything Save you from anything Save you from anything "
        android:textColor="#ffFF4081" />

    <camnter.newlife.widget.AutoAdjustSizeEditText
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:padding="16dp"
        android:text="Save you from anything Save you from anything Save you from anything Save you from anything "
        android:textColor="#ffFF4081" />

    <camnter.newlife.widget.AutoAdjustSizeEditText
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:padding="16dp"
        android:text="Save you from anything Save you from anything Save you from anything Save you from anything Save you from anything "
        android:textColor="#ffFF4081" />


</LinearLayout>

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AutoAdjustSizeEditTextActivity效果圖

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AutoAdjustSizeTextView

由於，EditText也是TextView的子類，所以用上面的AutoAdjustSizeEditText代碼一樣可以實現自動適配字體大小的TextView。

public class AutoAdjustSizeTextView extends TextView {

    // 最小字體
    private static final float DEFAULT_MIN_TEXT_SIZE = 8.0f;
    // 最大字體
    private static final float DEFAULT_MAX_TEXT_SIZE = 16.0f;

    private Paint textPaint;
    private float minTextSize = DEFAULT_MIN_TEXT_SIZE;
    private float maxTextSize = DEFAULT_MAX_TEXT_SIZE;

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

    private void initialise() {
        DisplayMetrics displayMetrics = this.getResources().getDisplayMetrics();
        if (this.textPaint == null) {
            this.textPaint = new Paint();
            this.textPaint.set(this.getPaint());
        }
        this.maxTextSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, this.maxTextSize, displayMetrics);
        if (DEFAULT_MIN_TEXT_SIZE >= maxTextSize) {
            this.maxTextSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, this.maxTextSize, displayMetrics);
        }
        this.maxTextSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, this.maxTextSize, displayMetrics);
        this.minTextSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, this.minTextSize, displayMetrics);
    }

    /**
     * Re size the font so the specified text fits in the text box * assuming
     * the text box is the specified width.
     */
    private void fitText(String text, int textWidth) {
        if (textWidth > 0) {
            // 單行可見文字寬度
            int availableWidth = textWidth - this.getPaddingLeft() - this.getPaddingRight();
            float trySize = maxTextSize;
            // 先用最大字體寫字
            textPaint.setTextSize(trySize);
            // 如果最大字體>最小字體 && 最大字體畫出字的寬度>單行可見文字寬度
            while ((trySize > minTextSize) && (textPaint.measureText(text) > availableWidth)) {
                // 最大字體小一號
                trySize -= 1;
                // 保證大於最小字體
                if (trySize <= minTextSize) {
                    trySize = minTextSize;
                    break;
                }
                // 再次用新字體寫字
                textPaint.setTextSize(trySize);
            }
            this.setTextSize(trySize);
        }
    }


    /**
     * 重寫setText
     * 每次setText的時候
     *
     * @param text
     * @param type
     */
    @Override
    public void setText(CharSequence text, BufferType type) {
        this.initialise();
        String textString = text.toString();
        float trySize = maxTextSize;
        if (this.textPaint == null) {
            this.textPaint = new Paint();
            this.textPaint.set(this.getPaint());
        }
        this.textPaint.setTextSize(trySize);
        // 計算設置內容前 內容佔據的寬度
        int textWidth = (int) this.textPaint.measureText(textString);
        // 拿到寬度和內容，進行調整
        this.fitText(textString, textWidth);
        super.setText(text, type);
    }


    @Override
    protected void onTextChanged(CharSequence text, int start, int before, int after) {
        super.onTextChanged(text, start, before, after);
        this.fitText(text.toString(), this.getWidth());
    }


    /**
     * This is called during layout when the size of this view has changed. If
     * you were just added to the view hierarchy, you're called with the old
     * values of 0.
     *
     * @param w    Current width of this view.
     * @param h    Current height of this view.
     * @param oldw Old width of this view.
     * @param oldh Old height of this view.
     */
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        // 如果當前view的寬度 != 原來view的寬度
        if (w != oldw) this.fitText(this.getText().toString(), w);
    }


}

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AutoAdjustSizeTextViewActivity

AutoAdjustSizeTextViewActivity

public class AutoAdjustSizeTextViewActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentView(R.layout.activity_auto_adjust_size_text_view);
    }
}

activity_auto_adjust_size_text_view.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <camnter.newlife.widget.AutoAdjustSizeTextView
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:padding="16dp"
        android:text="Save you from anything"
        android:textColor="#ffFF4081" />

    <camnter.newlife.widget.AutoAdjustSizeTextView
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:padding="16dp"
        android:text="Save you from anything Save you from anything"
        android:textColor="#ffFF4081" />

    <camnter.newlife.widget.AutoAdjustSizeTextView
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:padding="16dp"
        android:text="Save you from anything Save you from anything Save you from anything "
        android:textColor="#ffFF4081" />

    <camnter.newlife.widget.AutoAdjustSizeTextView
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:padding="16dp"
        android:text="Save you from anything Save you from anything Save you from anything Save you from anything "
        android:textColor="#ffFF4081" />

    <camnter.newlife.widget.AutoAdjustSizeTextView
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:padding="16dp"
        android:text="Save you from anything Save you from anything Save you from anything Save you from anything Save you from anything "
        android:textColor="#ffFF4081" />


</LinearLayout>

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AutoAdjustSizeTextViewActivity效果圖