HuePicker.java

/*
 * Copyright 2015 JBoss, by Red Hat, Inc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.uberfire.ext.widgets.common.client.colorpicker;

import com.google.gwt.event.dom.client.MouseDownEvent;
import com.google.gwt.event.dom.client.MouseDownHandler;
import com.google.gwt.event.dom.client.MouseMoveEvent;
import com.google.gwt.event.dom.client.MouseMoveHandler;
import com.google.gwt.event.dom.client.MouseOutEvent;
import com.google.gwt.event.dom.client.MouseOutHandler;
import com.google.gwt.event.dom.client.MouseUpEvent;
import com.google.gwt.event.dom.client.MouseUpHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.ui.Composite;
import org.uberfire.ext.widgets.common.client.colorpicker.canvas.Canvas;
import org.uberfire.ext.widgets.common.client.colorpicker.canvas.RenderingContext;

public class HuePicker extends Composite {

    private Canvas canvas;
    private int handleY = 90;
    private boolean mouseDown;

    public HuePicker() {
        canvas = new Canvas();
        canvas.setStylePrimaryName("subshell-HuePicker");
        canvas.setCanvasSize(26,
                             180);

        initWidget(canvas);

        canvas.addMouseDownHandler(new MouseDownHandler() {
            public void onMouseDown(MouseDownEvent event) {
                handleY = event.getRelativeY(canvas.getElement());
                drawGradient();
                fireHueChanged(getHue());

                mouseDown = true;
            }
        });
        canvas.addMouseMoveHandler(new MouseMoveHandler() {
            public void onMouseMove(MouseMoveEvent event) {
                if (mouseDown) {
                    handleY = event.getRelativeY(canvas.getElement());
                    drawGradient();
                    fireHueChanged(getHue());
                }
            }
        });
        canvas.addMouseUpHandler(new MouseUpHandler() {
            public void onMouseUp(MouseUpEvent event) {
                mouseDown = false;
            }
        });
        canvas.addMouseOutHandler(new MouseOutHandler() {
            public void onMouseOut(MouseOutEvent event) {
                mouseDown = false;
            }
        });
    }

    @Override
    protected void onAttach() {
        super.onAttach();
        drawGradient();
    }

    private void drawGradient() {
        RenderingContext ctx = canvas.getContext();

        // draw gradient
        ctx.setFillStyle("#ffffff");
        ctx.fillRect(0,
                     0,
                     26,
                     180);
        for (int y = 0; y <= 179; y++) {
            String hex = ColorUtils.hsl2hex(y * 2,
                                            100,
                                            100);
            ctx.setFillStyle("#" + hex);
            ctx.fillRect(3,
                         y,
                         20,
                         1);
        }

        // draw handle
        if (handleY >= 0) {
            ctx.setFillStyle("#000000");

            ctx.beginPath();
            ctx.moveTo(3,
                       handleY);
            ctx.lineTo(0,
                       handleY - 3);
            ctx.lineTo(0,
                       handleY + 3);
            ctx.closePath();
            ctx.fill();

            ctx.moveTo(23,
                       handleY);
            ctx.lineTo(26,
                       handleY - 3);
            ctx.lineTo(26,
                       handleY + 3);
            ctx.closePath();
            ctx.fill();
        }
    }

    public HandlerRegistration addHueChangedHandler(HueChangedHandler handler) {
        return addHandler(handler,
                          HueChangedEvent.getType());
    }

    private void fireHueChanged(int hue) {
        fireEvent(new HueChangedEvent(hue));
    }

    public int getHue() {
        return handleY * 2;
    }

    public void setHue(int hue) {
        handleY = (int) Math.min(Math.max(Math.round(hue / 2d),
                                          0d),
                                 179d);
        drawGradient();
        fireHueChanged(hue);
    }
}