FairEmail/colorpicker/src/main/java/com/flask/colorpicker/slider/AbsCustomSlider.java

package com.flask.colorpicker.slider;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.PorterDuff;
import androidx.annotation.DimenRes;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import com.flask.colorpicker.R;

public abstract class AbsCustomSlider extends View {
	protected Bitmap bitmap;
	protected Canvas bitmapCanvas;
	protected Bitmap bar;
	protected Canvas barCanvas;
	protected OnValueChangedListener onValueChangedListener;
	protected int barOffsetX;
	protected int handleRadius = 20;
	protected int barHeight = 5;
	protected float value = 1;
	protected boolean showBorder = false;

	private boolean inVerticalOrientation = false;

	public AbsCustomSlider(Context context) {
		super(context);
		init(context, null);
	}

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

	public AbsCustomSlider(Context context, AttributeSet attrs, int defStyleAttr) {
		super(context, attrs, defStyleAttr);
		init(context, attrs);
	}

	private void init(Context context, AttributeSet attrs) {
		TypedArray styledAttrs = context.getTheme().obtainStyledAttributes(
			attrs, R.styleable.AbsCustomSlider, 0, 0);
		try {
			inVerticalOrientation = styledAttrs.getBoolean(
				R.styleable.AbsCustomSlider_inVerticalOrientation, inVerticalOrientation);
		} finally {
			styledAttrs.recycle();
		}
	}

	protected void updateBar() {
		handleRadius = getDimension(R.dimen.default_slider_handler_radius);
		barHeight = getDimension(R.dimen.default_slider_bar_height);
		barOffsetX = handleRadius;

		if (bar == null)
			createBitmaps();
		drawBar(barCanvas);
		invalidate();
	}

	protected void createBitmaps() {
		int width;
		int height;
		if (inVerticalOrientation) {
			width = getHeight();
			height = getWidth();
		} else {
			width = getWidth();
			height = getHeight();
		}

		bar = Bitmap.createBitmap(Math.max(width - barOffsetX * 2, 1), barHeight, Bitmap.Config.ARGB_8888);
		barCanvas = new Canvas(bar);

		if (bitmap == null || bitmap.getWidth() != width || bitmap.getHeight() != height) {
			if (bitmap != null) bitmap.recycle();
			bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
			bitmapCanvas = new Canvas(bitmap);
		}
	}

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

		int width;
		int height;
		if (inVerticalOrientation) {
			width = getHeight();
			height = getWidth();

			canvas.rotate(-90);
			canvas.translate(-width, 0);
		} else {
			width = getWidth();
			height = getHeight();
		}

		if (bar != null && bitmapCanvas != null) {
			bitmapCanvas.drawColor(0, PorterDuff.Mode.CLEAR);
			bitmapCanvas.drawBitmap(bar, barOffsetX, (height - bar.getHeight()) / 2, null);

			float x = handleRadius + value * (width - handleRadius * 2);
			float y = height / 2f;
			drawHandle(bitmapCanvas, x, y);
			canvas.drawBitmap(bitmap, 0, 0, null);
		}
	}

	protected abstract void drawBar(Canvas barCanvas);

	protected abstract void onValueChanged(float value);

	protected abstract void drawHandle(Canvas canvas, float x, float y);

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		super.onSizeChanged(w, h, oldw, oldh);
		updateBar();
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		int widthMode = MeasureSpec.getMode(widthMeasureSpec);
		int width = 0;
		if (widthMode == MeasureSpec.UNSPECIFIED)
			width = widthMeasureSpec;
		else if (widthMode == MeasureSpec.AT_MOST)
			width = MeasureSpec.getSize(widthMeasureSpec);
		else if (widthMode == MeasureSpec.EXACTLY)
			width = MeasureSpec.getSize(widthMeasureSpec);

		int heightMode = MeasureSpec.getMode(heightMeasureSpec);
		int height = 0;
		if (heightMode == MeasureSpec.UNSPECIFIED)
			height = heightMeasureSpec;
		else if (heightMode == MeasureSpec.AT_MOST)
			height = MeasureSpec.getSize(heightMeasureSpec);
		else if (heightMode == MeasureSpec.EXACTLY)
			height = MeasureSpec.getSize(heightMeasureSpec);

		setMeasuredDimension(width, height);
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		switch (event.getAction()) {
			case MotionEvent.ACTION_DOWN:
			case MotionEvent.ACTION_MOVE: {
				if (bar != null) {
					if (inVerticalOrientation) {
						value = 1 - (event.getY() - barOffsetX) / bar.getWidth();
					} else {
						value = (event.getX() - barOffsetX) / bar.getWidth();
					}
					value = Math.max(0, Math.min(value, 1));
					onValueChanged(value);
					invalidate();
				}
				break;
			}
			case MotionEvent.ACTION_UP: {
				onValueChanged(value);
				if (onValueChangedListener != null)
					onValueChangedListener.onValueChanged(value);
				invalidate();
			}
		}
		return true;
	}

	protected int getDimension(@DimenRes int id) {
		return getResources().getDimensionPixelSize(id);
	}

	public void setShowBorder(boolean showBorder) {
		this.showBorder = showBorder;
	}

	public void setOnValueChangedListener(OnValueChangedListener onValueChangedListener) {
		this.onValueChangedListener = onValueChangedListener;
	}
}