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/**
* @license
* Copyright (C) 2021 The Android Open Source Project
*
* 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.
*/
import '@polymer/paper-button/paper-button';
import '@polymer/paper-card/paper-card';
import '@polymer/paper-checkbox/paper-checkbox';
import '@polymer/paper-dropdown-menu/paper-dropdown-menu';
import '@polymer/paper-item/paper-item';
import '@polymer/paper-listbox/paper-listbox';
import './gr-overview-image';
import './gr-zoomed-image';
import {
css,
customElement,
html,
internalProperty,
LitElement,
property,
PropertyValues,
query,
} from 'lit-element';
import {classMap} from 'lit-html/directives/class-map';
import {StyleInfo, styleMap} from 'lit-html/directives/style-map';
import {Dimensions, fitToFrame, FrameConstrainer, Point, Rect} from './util';
const DRAG_DEAD_ZONE_PIXELS = 5;
/**
* This components allows the user to rapidly switch between two given images
* rendered in the same location, to make subtle differences more noticeable.
* Images can be magnified to compare details.
*/
@customElement('gr-image-viewer')
export class GrImageViewer extends LitElement {
// URL for the image to use as base.
@property({type: String}) baseUrl = '';
// URL for the image to use as revision.
@property({type: String}) revisionUrl = '';
@internalProperty() protected baseSelected = true;
@internalProperty() protected scaledSelected = true;
@internalProperty() protected followMouse = false;
@internalProperty() protected scale = 1;
@internalProperty() protected checkerboardSelected = true;
@internalProperty() protected zoomedImageStyle: StyleInfo = {};
@query('.imageArea') protected imageArea!: HTMLDivElement;
@query('gr-zoomed-image') protected zoomedImage!: Element;
@query('#source-image') protected sourceImage!: HTMLImageElement;
private imageSize: Dimensions = {width: 0, height: 0};
@internalProperty()
protected magnifierSize: Dimensions = {width: 0, height: 0};
@internalProperty()
protected magnifierFrame: Rect = {
origin: {x: 0, y: 0},
dimensions: {width: 0, height: 0},
};
@internalProperty()
protected overviewFrame: Rect = {
origin: {x: 0, y: 0},
dimensions: {width: 0, height: 0},
};
protected readonly zoomLevels: Array<'fit' | number> = [
'fit',
1,
1.25,
1.5,
1.75,
2,
];
@internalProperty() protected grabbing = false;
private ownsMouseDown = false;
private centerOnDown: Point = {x: 0, y: 0};
private pointerOnDown: Point = {x: 0, y: 0};
private readonly frameConstrainer = new FrameConstrainer();
private readonly resizeObserver = new ResizeObserver(
(entries: ResizeObserverEntry[]) => {
for (const entry of entries) {
if (entry.target === this.imageArea) {
this.magnifierSize = {
width: entry.contentRect.width,
height: entry.contentRect.height,
};
}
}
}
);
static styles = css`
:host {
display: flex;
width: 100%;
height: 100%;
box-sizing: border-box;
font-size: var(--font-size-normal);
--image-border-width: 2px;
}
.imageArea {
box-sizing: border-box;
flex-grow: 1;
overflow: hidden;
display: flex;
flex-direction: column;
align-items: center;
margin: var(--spacing-m);
padding: var(--image-border-width);
max-height: 100%;
}
#spacer {
visibility: hidden;
}
gr-zoomed-image {
border: var(--image-border-width) solid;
margin: calc(-1 * var(--image-border-width));
box-sizing: content-box;
position: absolute;
overflow: hidden;
cursor: pointer;
}
gr-zoomed-image.base {
border-color: var(--base-image-border-color, rgb(255, 205, 210));
}
gr-zoomed-image.revision {
border-color: var(--revision-image-border-color, rgb(170, 242, 170));
}
.checkerboard {
--square-size: var(--checkerboard-square-size, 10px);
--square-color: var(--checkerboard-square-color, #808080);
background-color: var(--checkerboard-background-color, #aaaaaa);
background-image: linear-gradient(
45deg,
var(--square-color) 25%,
transparent 25%
),
linear-gradient(-45deg, var(--square-color) 25%, transparent 25%),
linear-gradient(45deg, transparent 75%, var(--square-color) 75%),
linear-gradient(-45deg, transparent 75%, var(--square-color) 75%);
background-size: calc(var(--square-size) * 2) calc(var(--square-size) * 2);
background-position: 0 0, 0 var(--square-size),
var(--square-size) calc(-1 * var(--square-size)),
calc(-1 * var(--square-size)) 0;
}
.controls {
flex-grow: 0;
display: flex;
flex-direction: column;
align-self: flex-start;
margin: var(--spacing-m);
padding-bottom: var(--spacing-xl);
}
paper-button {
padding: var(--spacing-m);
font: var(--image-diff-button-font);
text-transform: var(--image-diff-button-text-transform, uppercase);
}
paper-button[unelevated] {
color: var(--primary-button-text-color);
background-color: var(--primary-button-background-color);
}
paper-button[outlined] {
color: var(--primary-button-background-color);
border-color: var(--primary-button-background-color);
}
#version-switcher {
display: flex;
margin: var(--spacing-xl);
}
#version-switcher paper-button {
flex-basis: 0;
flex-grow: 1;
margin: 0;
}
#version-explanation {
color: var(--deemphasized-text-color);
text-align: center;
margin: var(--spacing-xl);
}
gr-overview-image {
min-width: 200px;
min-height: 150px;
}
#zoom-control {
margin: 0 var(--spacing-xl);
}
#follow-mouse {
margin: var(--spacing-m) var(--spacing-xl) 0;
}
`;
render() {
const src = this.baseSelected ? this.baseUrl : this.revisionUrl;
const sourceImage = html`
<img
id="source-image"
src="${src}"
class="${classMap({
checkerboard: this.checkerboardSelected,
})}"
@load="${this.updateSizes}"
/>
`;
const versionExplanation = html`
<div id="version-explanation">
This file is being ${this.revisionUrl ? 'added' : 'deleted'}.
</div>
`;
// This uses the unelevated and outlined attributes from mwc-button with
// manual styling, for a more seamless transition later.
const versionToggle = html`
<div id="version-switcher">
<paper-button
class="left"
?unelevated=${this.baseSelected}
?outlined=${!this.baseSelected}
@click="${this.selectBase}"
>
Base
</paper-button>
<paper-button
class="right"
?unelevated=${!this.baseSelected}
?outlined=${this.baseSelected}
@click="${this.selectRevision}"
>
Revision
</paper-button>
</div>
`;
const versionSwitcher = html`
${this.baseUrl && this.revisionUrl ? versionToggle : versionExplanation}
`;
const overviewImage = html`
<gr-overview-image
.frameRect="${this.overviewFrame}"
@center-updated="${this.onOverviewCenterUpdated}"
>
<img src="${src}" class="checkerboard" />
</gr-overview-image>
`;
const zoomControl = html`
<paper-dropdown-menu id="zoom-control" label="Zoom">
<paper-listbox
slot="dropdown-content"
selected="fit"
attr-for-selected="value"
@selected-changed="${this.zoomControlChanged}"
>
${this.zoomLevels.map(
zoomLevel => html`
<paper-item value="${zoomLevel}">
${zoomLevel === 'fit' ? 'Fit' : `${zoomLevel * 100}%`}
</paper-item>
`
)}
</paper-listbox>
</paper-dropdown-menu>
`;
const followMouse = html`
<paper-checkbox
id="follow-mouse"
?checked="${this.followMouse}"
@change="${this.followMouseChanged}"
>
Magnifier follows mouse
</paper-checkbox>
`;
/*
* We want the content to fill the available space until it can display
* without being cropped, the maximum of which will be determined by
* (max-)width and (max-)height constraints on the host element; but we
* are also limiting the displayed content to the measured dimensions of
* the host element without overflow, so we need something else to take up
* the requested space unconditionally.
*/
const spacerScale = Math.max(this.scale, 1);
const spacerWidth = this.imageSize.width * spacerScale;
const spacerHeight = this.imageSize.height * spacerScale;
const spacer = html`
<div
id="spacer"
style="${styleMap({
width: `${spacerWidth}px`,
height: `${spacerHeight}px`,
})}"
></div>
`;
// To pass CSS mixins for @apply to Polymer components, they need to be
// wrapped in a <custom-style>.
const customStyle = html`
<custom-style>
<style>
paper-button.left {
--paper-button: {
border-radius: 4px 0 0 4px;
border-width: 1px 0 1px 1px;
}
}
paper-button.left[outlined] {
--paper-button: {
border-radius: 4px 0 0 4px;
border-width: 1px 0 1px 1px;
border-style: solid;
border-color: var(--primary-button-background-color);
}
}
paper-button.right {
--paper-button: {
border-radius: 0 4px 4px 0;
border-width: 1px 1px 1px 0;
}
}
paper-button.right[outlined] {
--paper-button: {
border-radius: 0 4px 4px 0;
border-width: 1px 1px 1px 0;
border-style: solid;
border-color: var(--primary-button-background-color);
}
}
paper-item {
cursor: pointer;
--paper-item-min-height: 48;
--paper-item: {
min-height: 48px;
padding: 0 var(--spacing-xl);
}
--paper-item-focused-before: {
background-color: var(--selection-background-color);
}
--paper-item-focused: {
background-color: var(--selection-background-color);
}
}
}
paper-item:hover {
background-color: var(--hover-background-color);
}
</style>
</custom-style>
`;
return html`
${customStyle}
<div class="imageArea" @mousemove="${this.mousemoveMagnifier}">
<gr-zoomed-image
class="${classMap({
base: this.baseSelected,
revision: !this.baseSelected,
})}"
style="${styleMap({
...this.zoomedImageStyle,
cursor: this.grabbing ? 'grabbing' : 'pointer',
})}"
.scale="${this.scale}"
.frameRect="${this.magnifierFrame}"
@mousedown="${this.mousedownMagnifier}"
@mouseup="${this.mouseupMagnifier}"
@mousemove="${this.mousemoveMagnifier}"
@mouseleave="${this.mouseleaveMagnifier}"
@dragstart="${this.dragstartMagnifier}"
>
${sourceImage}
</gr-zoomed-image>
${spacer}
</div>
<paper-card class="controls">
${versionSwitcher} ${overviewImage} ${zoomControl}
${!this.scaledSelected ? followMouse : ''}
</paper-card>
`;
}
firstUpdated() {
this.resizeObserver.observe(this.imageArea, {box: 'content-box'});
}
// We don't want property changes in updateSizes() to trigger infinite update
// loops, so we perform this in update() instead of updated().
update(changedProperties: PropertyValues) {
if (!this.baseUrl) this.baseSelected = false;
if (!this.revisionUrl) this.baseSelected = true;
this.updateSizes();
super.update(changedProperties);
}
updated(changedProperties: PropertyValues) {
if (
(changedProperties.has('baseUrl') && this.baseSelected) ||
(changedProperties.has('revisionUrl') && !this.baseSelected)
) {
this.frameConstrainer.requestCenter({x: 0, y: 0});
}
}
selectBase() {
if (!this.baseUrl) return;
this.baseSelected = true;
}
selectRevision() {
if (!this.revisionUrl) return;
this.baseSelected = false;
}
toggleImage() {
if (this.baseUrl && this.revisionUrl) {
this.baseSelected = !this.baseSelected;
}
}
zoomControlChanged(event: CustomEvent) {
const value = event.detail.value;
if (!value) return;
if (value === 'fit') {
this.scaledSelected = true;
}
if (value > 0) {
this.scaledSelected = false;
this.scale = value;
}
this.updateSizes();
}
followMouseChanged() {
this.followMouse = !this.followMouse;
}
mousedownMagnifier(event: MouseEvent) {
if (event.buttons === 1) {
this.ownsMouseDown = true;
this.centerOnDown = this.frameConstrainer.getCenter();
this.pointerOnDown = {
x: event.clientX,
y: event.clientY,
};
}
}
mouseupMagnifier(event: MouseEvent) {
const offsetX = event.clientX - this.pointerOnDown.x;
const offsetY = event.clientY - this.pointerOnDown.y;
const distance = Math.max(Math.abs(offsetX), Math.abs(offsetY));
// Consider very short drags as clicks. These tend to happen more often on
// external mice.
if (this.ownsMouseDown && distance < DRAG_DEAD_ZONE_PIXELS) {
this.toggleImage();
}
this.grabbing = false;
this.ownsMouseDown = false;
}
mousemoveMagnifier(event: MouseEvent) {
if (event.buttons === 1 && this.ownsMouseDown) {
this.handleMagnifierDrag(event);
return;
}
if (this.followMouse) {
this.handleFollowMouse(event);
return;
}
}
private handleMagnifierDrag(event: MouseEvent) {
this.grabbing = true;
const offsetX = event.clientX - this.pointerOnDown.x;
const offsetY = event.clientY - this.pointerOnDown.y;
this.frameConstrainer.requestCenter({
x: this.centerOnDown.x - offsetX / this.scale,
y: this.centerOnDown.y - offsetY / this.scale,
});
this.updateFrames();
}
private handleFollowMouse(event: MouseEvent) {
const rect = this.imageArea!.getBoundingClientRect();
const offsetX = event.clientX - rect.left;
const offsetY = event.clientY - rect.top;
const fractionX = offsetX / rect.width;
const fractionY = offsetY / rect.height;
this.frameConstrainer.requestCenter({
x: this.imageSize.width * fractionX,
y: this.imageSize.height * fractionY,
});
this.updateFrames();
}
mouseleaveMagnifier() {
this.grabbing = false;
this.ownsMouseDown = false;
}
dragstartMagnifier(event: DragEvent) {
event.preventDefault();
}
onOverviewCenterUpdated(event: CustomEvent) {
this.frameConstrainer.requestCenter({
x: event.detail.x as number,
y: event.detail.y as number,
});
this.updateFrames();
}
updateFrames() {
this.magnifierFrame = this.frameConstrainer.getUnscaledFrame();
this.overviewFrame = this.frameConstrainer.getScaledFrame();
}
updateSizes() {
if (!this.sourceImage || !this.sourceImage.complete) return;
this.imageSize = {
width: this.sourceImage.naturalWidth || 0,
height: this.sourceImage.naturalHeight || 0,
};
this.frameConstrainer.setBounds(this.imageSize);
if (this.scaledSelected) {
const fittedImage = fitToFrame(this.imageSize, this.magnifierSize);
this.scale = Math.min(fittedImage.scale, 1);
}
this.frameConstrainer.setScale(this.scale);
const scaledImageSize = {
width: this.imageSize.width * this.scale,
height: this.imageSize.height * this.scale,
};
const width = Math.min(this.magnifierSize.width, scaledImageSize.width);
const height = Math.min(this.magnifierSize.height, scaledImageSize.height);
this.frameConstrainer.setFrameSize({width, height});
this.updateFrames();
this.zoomedImageStyle = {
...this.zoomedImageStyle,
width: `${width}px`,
height: `${height}px`,
};
}
}
declare global {
interface HTMLElementTagNameMap {
'gr-image-viewer': GrImageViewer;
}
}