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// Copyright (C) 2018 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.
// TODO(hjd): Dedupe these.
const SLICE_HEIGHT = 32;
const TRACK_PADDING = 5;
/**
* Checker board the range [leftPx, rightPx].
*/
export function checkerboard(
ctx: CanvasRenderingContext2D, leftPx: number, rightPx: number): void {
const widthPx = rightPx - leftPx;
ctx.font = '12px Google Sans';
ctx.fillStyle = '#eee';
ctx.fillRect(leftPx, TRACK_PADDING, widthPx, SLICE_HEIGHT);
ctx.fillStyle = '#666';
ctx.textBaseline = 'alphabetic';
ctx.fillText(
'loading...',
leftPx + widthPx / 2,
TRACK_PADDING + SLICE_HEIGHT / 2,
widthPx);
}
/**
* Checker board everything between [startPx, endPx] except [leftPx, rightPx].
*/
export function checkerboardExcept(
ctx: CanvasRenderingContext2D,
startPx: number,
endPx: number,
leftPx: number,
rightPx: number): void {
// [leftPx, rightPx] doesn't overlap [startPx, endPx] at all:
if (rightPx <= startPx || leftPx >= endPx) {
checkerboard(ctx, startPx, endPx);
return;
}
// Checkerboard [startPx, leftPx]:
if (leftPx > startPx) {
checkerboard(ctx, startPx, leftPx);
}
// Checkerboard [rightPx, endPx]:
if (rightPx < endPx) {
checkerboard(ctx, rightPx, endPx);
}
}
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