How can I resize image to fit container height on button-press?

Question

So I'm trying to tweak my Anki flashcards by adding stroke-order diagrams for kanjis.

The diagrams are generated by a plugin called Kanji Colorizer .

Love the plugin, but the images are

• are too big
• stack vertically

So... I want to create a scroll-box that contains the images horizontally and scrolls horizontally if there are too many kanji to display side-by-side.

I think I have succeeded in that, at least. (see code below).

The problem now is that although the box scrolls horizontally (and would vertically too, if I enabled it), the images remain as big as they are. Meaning I need to allow vertical scrolling or else accept useless cropped images.

How do I resize the images to fit the box?

To clarify:

The html looks like this:

<span style="font-size: 20px; "> {{Meaning}} </span>

<hr id=answer>
<tts style="display:none" service="android" voice="ja_JP">{{Expression}}</tts>
<span style="font-size: 40px; ">
{{furigana:Reading}}
</span>
<br>
<div id = "output"></div>
<br>
<button onclick="showHideStrokeOrder()">Stroke Order</button>
<center>
<div id="scrollboxStrokeOrder" style="border:1px solid black;height:150px;width:100%;white-space:nowrap;overflow-y:hidden;overflow-x:auto;display:none">
    <div id='strokeOrderPictures'>{{Stroke Order Diagram}}</div>
</div>
</center>

<script>
function showHideStrokeOrder() {
    var out = document.getElementById("output");

    var scrollbox = document.getElementById("scrollboxStrokeOrder");
    if (scrollbox.style.display === "none") {
       scrollbox.style.display = "block";
    } else {
        scrollbox.style.display = "none";
    };

    var imgs = document.getElementById('strokeOrderPictures');

    var maxHeight= parseFloat(scrollbox.style.height);
    var imgsHeight = imgs.firstChild.height;

    out.innerHTML = "scrollbox height = " + maxHeight + ", imgs height = " + imgsHeight;

    if(imgsHeight > maxHeight) {
        const scale = maxHeight / imgsHeight;
        out.innerHTML += ", scaling = " +scale;

        //this doesn't work and should be replaced, just to clarify intent:
        imgs.style.height = maxHeight;
        imgs.style.width = 'auto';
    };
}
</script>

Where {{Stroke Order Diagram}} is a reference to the card's field where the diagram images have been generated in. In the example above, it contains two individual pictures, one for each kanji).

UPDATE : shared the example as a downloadable deck, if you want to try it out:

https://ankiweb.net/shared/info/1180304154

Answer 1

For anybody looking for something similar in the future, here's the final code:

<span style="font-size: 20px; "> {{Meaning}} </span>

<hr id=answer>
<tts style="display:none" service="android" voice="ja_JP">{{Expression}}</tts>
<span style="font-size: 40px; ">
{{furigana:Reading}}
</span>
<br>
<button onclick="showHideStrokeOrder()">Stroke Order</button>
<center>
<div id="scrollboxStrokeOrder" style="border:1px solid black;height:150px;width:100%;white-space: nowrap;overflow-y:hidden;overflow-x:auto;display:none">
    <div id='strokeOrderPictures'>{{Stroke Order Diagram}}</div>
</div>
</center>


<script>
function showHideStrokeOrder() {    
    var scrollbox = document.getElementById("scrollboxStrokeOrder");
    if (scrollbox.style.display === "none") {
       scrollbox.style.display = "block";
       resizeStrokeOrderDiagrams();
    } else {
        scrollbox.style.display = "none";
    };
}
function resizeStrokeOrderDiagrams(){
    var scrollbox = document.getElementById("scrollboxStrokeOrder");
    var imgs = document.getElementById('strokeOrderPictures');

    var maxHeight= parseFloat(scrollbox.style.height)
    var imgsHeight = imgs.firstChild.height

    if(imgsHeight > maxHeight) {
        var diagrams = imgs.getElementsByTagName("img");

        for( i=0; i< diagrams.length; i++ ) {
            var d = diagrams[i];
            d.height= maxHeight -5;
        }
    };

}
</script>

Answer 2

Match image height to container

By jQuery:

$("#myImg").prop("height", $("#myContainer").prop("height"));

By DOM:

document.getElementById("myImg").height=
    document.getElementById("myContainer").height;

Browser HTML behavior with images is pretty generous. This directly resizes the image to the container, regardless of the container's height (including making it bigger - you may want to code more for that if you don't want that behavior)