Android 实现更改字体大小

• 调节字体大小的自定义 Seekbar（CustomSeekbar .java）

package com.fcsc.fcscuilib.customview;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import com.fcsc.fcscuilib.R;

import java.util.ArrayList;
import java.util.List;

/**
 * 调节字体大小的自定义Seekbar
 */
public class CustomSeekbar extends View {

    private static final String A = "A";
    private static final String strStandard = "标准";

    private static final int DEFAULT_LINE_COLOR = Color.BLACK;
    private static final int DEFAULT_COUNT = 5;
    private static final int DEFAULT_CIRCLE_COLOR = Color.WHITE;
    private static final int DEFAULT_POSITION = 1;
    private static final int DEFAULT_LINE_HEIGHT = 16;

    private static int DEFAULT_LINE_WIDTH;
    private static int DEFAULT_CIRCLE_RADIUS;

    // 一共有多少格
    private int mMax = 5;
    // 线条颜色
    private int mLineColor;
    // 线条粗细
    private int mLineWidth;
    // 突出部分的线条高度
    private int mLineHeight;
    // 指标的圆半径
    private int mCircleRadius;
    // 指标的颜色
    private int mCircleColor;
    // 一段的宽度，根据总宽度和总格数计算得来
    private int mItemWidth;
    // 控件的宽高
    private int mHeight;
    private int mWidth;
    // 当前所在位置
    private int mCurrentPosition = DEFAULT_POSITION;
    // 画笔
    private Paint mLinePaint;
    private Paint mCirclePaint;
    // 滑动过程中x坐标
    private float mCurrentX = 0;
    // 有效数据点
    private List<Point> mPoints = new ArrayList<>();

    private float mCircleX;
    private float mCircleY;

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

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

    private void init(Context context, AttributeSet attrs) {
        // initDefault
        DEFAULT_LINE_WIDTH = dp2px(context, 2);
        DEFAULT_CIRCLE_RADIUS = dp2px(context, 32);

        mLineColor = Color.rgb(33, 33, 33);
        mLineWidth = dp2px(context, 0);
        mCircleColor = Color.WHITE;

        // initCustomAttrs
        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.CustomSeekbar);
        final int N = typedArray.getIndexCount();
        for (int i = 0; i < N; i++) {
            initCustomAttr(typedArray.getIndex(i), typedArray);
        }
        typedArray.recycle();

        // 初始化画笔
        mLinePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mLinePaint.setColor(mLineColor);
        mLinePaint.setStyle(Paint.Style.FILL_AND_STROKE);
        mLinePaint.setStrokeWidth(mLineWidth);

        mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mCirclePaint.setColor(mCircleColor);
        mCirclePaint.setStyle(Paint.Style.FILL);
        // 设置阴影效果
        setLayerType(LAYER_TYPE_SOFTWARE, null);
        mCirclePaint.setShadowLayer(2, 0, 0, Color.GRAY);
    }

    private void initCustomAttr(int attr, TypedArray typedArray) {
        if (attr == R.styleable.CustomSeekbar_customLineColor) {
            mLineColor = typedArray.getColor(attr, DEFAULT_LINE_COLOR);
        } else if (attr == R.styleable.CustomSeekbar_circleColor) {
            mCircleColor = typedArray.getColor(attr, DEFAULT_CIRCLE_COLOR);
        } else if (attr == R.styleable.CustomSeekbar_customLineWidth) {
            mLineWidth = typedArray.getDimensionPixelSize(attr, DEFAULT_LINE_WIDTH);
        } else if (attr == R.styleable.CustomSeekbar_circleRadius) {
            mCircleRadius = typedArray.getDimensionPixelSize(attr, DEFAULT_CIRCLE_RADIUS);
        } else if (attr == R.styleable.CustomSeekbar_totalCount) {
            mMax = typedArray.getInteger(attr, DEFAULT_COUNT);
        }
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        mHeight = h;
        mWidth = w;
        mCircleY = mHeight / 2;
        mLineHeight = DEFAULT_LINE_HEIGHT;
        // 横线宽度是总宽度-2个圆的半径
        mItemWidth = (w - 2 * mCircleRadius) / mMax;
        // 把可点击点保存起来
        for (int i = 0; i <= mMax; i++) {
            mPoints.add(new Point(mCircleRadius + i * mItemWidth, mHeight / 2));
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        // 先画中间的横线
        canvas.drawLine(mPoints.get(0).x, mHeight / 2, mPoints.get(mPoints.size() - 1).x, mHeight / 2, mLinePaint);
        // 绘制刻度
        for (Point point : mPoints) {
            canvas.drawLine(point.x, mHeight / 2 - mLineHeight, point.x, mHeight / 2 + mLineHeight, mLinePaint);
        }
        mLinePaint.setTextSize(40);
        canvas.drawText(A, mPoints.get(0).x - mLinePaint.measureText(A)/2, mPoints.get(0).y - ((Math.max(mLineHeight, mCircleRadius) + 16)), mLinePaint);
        mLinePaint.setTextSize(56);
        canvas.drawText(strStandard, mPoints.get(2).x - mLinePaint.measureText(strStandard)/2, mPoints.get(2).y - ((Math.max(mLineHeight, mCircleRadius) + 16)), mLinePaint);
        mLinePaint.setTextSize(86);
        canvas.drawText(A, mPoints.get(5).x - mLinePaint.measureText(A)/2, mPoints.get(5).y - ((Math.max(mLineHeight, mCircleRadius) + 16)), mLinePaint);
        // 画圆
        if (canMove) {
            // 随手指滑动过程
            if (mCurrentX < mCircleRadius) {
                mCurrentX = mCircleRadius;
            }
            if (mCurrentX > mWidth - mCircleRadius) {
                mCurrentX = mWidth - mCircleRadius;
            }
            mCircleX = mCurrentX;
        } else {
            // 最终
            mCircleX = mPoints.get(mCurrentPosition).x;
        }
        // 实体圆
        canvas.drawCircle(mCircleX, mCircleY, mCircleRadius, mCirclePaint);
    }

    float downX = 0;
    private boolean canMove = false;

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // 过滤掉不合法的坐标
//        if (event.getX() < mCircleRadius || event.getX() > mWidth - mCircleRadius) {
//            return false;
//        }
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                // 判断是否是数据点
                downX = event.getX();
                canMove = isDownOnCircle(downX);
                break;
            case MotionEvent.ACTION_MOVE:
                if (canMove) {
                    mCurrentX = event.getX();
                    invalidate();
                }
                break;
            case MotionEvent.ACTION_UP:
                // 手指抬起之后就圆就不能在非有效点
                mCurrentX = 0;
                float upX = event.getX();
                if (canMove) {
                    // 是滑动过来的，要判断距离哪个有效点最近，就滑动到哪个点
                    Point targetPoint = getNearestPoint(upX);
                    if (targetPoint != null) {
                        invalidate();
                    }
                } else {
                    if (Math.abs(downX - upX) < 30) {
                        Point point = isValidPoint(upX);
                        if (point != null) {
                            invalidate();
                        }
                    }
                }
                if (onPointResultListener != null) {
                    onPointResultListener.onPointResult(mCurrentPosition);
                }
                downX = 0;
                canMove = false;
                break;
        }
        return true;
    }

    /**
     * 滑动抬起之后，要滑动到最近的一个点那里
     *
     * @param x
     * @return
     */
    private Point getNearestPoint(float x) {
        for (int i = 0; i < mPoints.size(); i++) {
            Point point = mPoints.get(i);
            if (Math.abs(point.x - x) < mItemWidth / 2) {
                mCurrentPosition = i;
                return point;
            }
        }
        return null;
    }

    /**
     * 判断是否点击到圆上
     *
     * @param x
     * @return
     */
    private boolean isDownOnCircle(float x) {
        return Math.abs(mPoints.get(mCurrentPosition).x - x) < mCircleRadius;
    }

    /**
     * 判断是否是有效的点击点
     *
     * @param x
     */
    private Point isValidPoint(float x) {
        for (int i = 0; i < mPoints.size(); i++) {
            Point point = mPoints.get(i);
            if (Math.abs(point.x - x) < 30) {
                mCurrentPosition = i;
                return point;
            }
        }
        return null;
    }

    /**
     * 设置当前的位置
     *
     * @param position
     */
    public void setCurrntPosition(int position) {
        mCurrentPosition = position;
    }

    public void setOnPointResultListener(OnPointResultListener onPointResultListener) {
        this.onPointResultListener = onPointResultListener;
    }

    private OnPointResultListener onPointResultListener;

    public interface OnPointResultListener {
        void onPointResult(int position);
    }

    public static int dp2px(Context context, float dipValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dipValue * scale + 0.5f);
    }
}

• FontChangeActivity.java

package com.fcsc.commine.activity;

import android.app.Activity;
import android.content.Intent;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.util.DisplayMetrics;
import android.widget.ImageView;
import android.widget.TextView;

import com.alibaba.android.arouter.facade.annotation.Route;
import com.fcsc.commine.R;
import com.fcsc.commine.R2;
import com.fcsc.common.FcscKey;
import com.fcsc.fcscbaseframwork.base.BaseActivity;
import com.fcsc.fcscbaseframwork.base.IPresenter;
import com.fcsc.fcscbaseframwork.base.PageManager;
import com.fcsc.fcscbaseframwork.util.MMKVHelper;
import com.fcsc.fcscuilib.customview.CustomSeekbar;

import java.util.Stack;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import butterknife.BindView;

/**
 * 改变字体大小的activity
 * @author pengyanni
 */
@Route(path = "/commine/fontchangeactivity")
public class FontChangeActivity extends BaseActivity {

    private float[] mFontSize = {0.84f, 0.92f, 1.0f, 1.04f, 1.08f, 1.12f};

    @BindView(R2.id.custom_seekbar_fontsize)
    CustomSeekbar customSeekbar;
    @BindView(R2.id.tv_commom_title)
    TextView tvTitle;
    @BindView(R2.id.img_commom_back)
    ImageView imgBack;

    /**
     * 默认标准
     */
    private float newFontScale;

    @Override
    protected void initViewAndEvent() {

        tvTitle.setText("字体大小");
        imgBack.setOnClickListener(v -> finish());
        mImmersionBar.statusBarColor(R.color.colorPrimary).init();

        float oldFontScale = MMKVHelper.getInstance().getFloat(FcscKey.KEY_FONT_SCALE, 1.0f);
        for (int index = 0; index < mFontSize.length; index++) {
            if (mFontSize[index] == oldFontScale) {
                customSeekbar.setCurrntPosition(index);
            }
        }

        newFontScale = oldFontScale;

        customSeekbar.setOnPointResultListener(position -> {
            newFontScale = mFontSize[position];
            if (newFontScale != oldFontScale) {
                updateAppFontSize(newFontScale);
                startActivity(new Intent(this, FontChangeActivity.class));
                overridePendingTransition(R.anim.anim_in, R.anim.anim_out);
                finish();
            }
        });

    }

    @Override
    protected void initDatas() {

    }

    @Nullable
    @Override
    protected IPresenter createPresenter() {
        return null;
    }

    @NonNull
    @Override
    protected int getLayoutId() {
        return R.layout.activity_font_change;
    }

    /**
     * 更新app的字体缩放
     *
     * @param newFontScale 缩放比例
     */
    private void updateAppFontSize(float newFontScale) {

        Stack<Activity> activityStack = PageManager.getInstance().getAllActivities();
        if (activityStack != null) {
            for (Activity activity : activityStack) {
                if (activity instanceof FontChangeActivity) {
                    continue;
                }
                Resources resources = activity.getResources();
                if (resources != null) {
                    Configuration configuration = activity.getResources().getConfiguration();
                    configuration.fontScale = newFontScale;
                    DisplayMetrics metrics = new DisplayMetrics();
                    activity.getWindowManager().getDefaultDisplay().getMetrics(metrics);
                    metrics.scaledDensity = configuration.fontScale * metrics.density;
                    resources.updateConfiguration(configuration, metrics);
                    activity.recreate();
                }
            }
            MMKVHelper.getInstance().saveFloat(FcscKey.KEY_FONT_SCALE, newFontScale);
        }
    }
}

• activity_font_change.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:app="http://schemas.android.com/apk/res-auto"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:background="@color/windowBackground"
              android:fitsSystemWindows="true"
              android:orientation="vertical">

    <include layout="@layout/commom_title_bar"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:lineSpacingExtra="10dp"
        android:layout_marginTop="50dp"
        android:paddingLeft="@dimen/aroundMargins"
        android:paddingRight="@dimen/aroundMargins"
        android:singleLine="false"
        android:text="@string/change_fontsize_description"
        android:textAppearance="?android:textAppearanceMedium"
        android:layout_weight="1"
        android:textColor="@color/textMainColor"/>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="150dp"
        android:layout_gravity="bottom"
        android:background="@color/viewBackground"
        android:padding="16dp">

        <com.fcsc.fcscuilib.customview.CustomSeekbar
            android:id="@+id/custom_seekbar_fontsize"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            app:circleRadius="12dp"
            app:customLineColor="@color/textMainColor"
            app:totalCount="5"/>

    </FrameLayout>

</LinearLayout>

• 效果