回答編集履歴
2
コード修正
answer
CHANGED
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@@ -28,7 +28,7 @@
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```javascript
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'use strict';
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const pdfInput = document.getElementById('pdfInput');
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-
const dpiInput = document.getElementById('dpiInput')
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31
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+
const dpiInput = document.getElementById('dpiInput');
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async function convertToJpeg () {
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// FileReaderオブジェクト生成
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const reader = new FileReader();
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1
コメント整備
answer
CHANGED
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@@ -28,20 +28,24 @@
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28
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```javascript
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'use strict';
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const pdfInput = document.getElementById('pdfInput');
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31
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+
const dpiInput = document.getElementById('dpiInput'):
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async function convertToJpeg () {
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// FileReaderオブジェクト生成
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const reader = new FileReader();
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// loadイベント登録
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reader.addEventListener('load', async function onLoad (event) {
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const dpi = parseInt(dpiInput.value);
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// FileReaderで読み取ったデータを取得
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const url = reader.result;
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-
const dpi = parseInt(document.getElementById('dpiInput').value);
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const loadingTask = pdfjsLib.getDocument(url);
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const pdf = await loadingTask.promise;
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const pageCount = pdf.numPages;
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const canvas = document.createElement('canvas');
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const ctx = canvas.getContext('2d');
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let page, viewport, scale, renderContext, imageData, link;
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-
for (let pageNumber = 1; pageNumber <= pageCount; pageNumber++) {
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for (let pageNumber = 1; pageNumber <= pageCount; pageNumber ++) {
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page = await pdf.getPage(pageNumber);
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-
viewport = page.getViewport({
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+
viewport = page.getViewport({scale: 1.0});
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scale = dpi / 72; // Convert DPI to scale factor
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canvas.width = Math.floor(viewport.width * scale);
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canvas.height = Math.floor(viewport.height * scale);
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@@ -51,12 +55,14 @@
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};
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await page.render(renderContext).promise;
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imageData = canvas.toDataURL('image/jpeg', 1.0);
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// appendChild無しでも行けたはずです
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link = document.createElement('a');
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link.href = imageData;
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link.download = `page_${pageNumber}.jpg`;
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link.click();
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}
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}, false);
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// DataURLとして読み込み(files.lengthなどで異常判定はした方が良いかもです)
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reader.readAsDataURL(pdfInput.files[0]);
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}
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```
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