From 0c0488cc79f363a2aaebac14d9edca76faf492fc Mon Sep 17 00:00:00 2001
From: Guilhem Moulin <guilhem@fripost.org>
Date: Mon, 22 Jan 2024 01:58:37 +0100
Subject: Add ability to grab and move popovers.

---
 main.js   | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++-----------
 style.css | 18 +++++++++++++++++
 2 files changed, 74 insertions(+), 11 deletions(-)

diff --git a/main.js b/main.js
index 4ed491f..051ef5f 100644
--- a/main.js
+++ b/main.js
@@ -807,9 +807,54 @@ map.addLayer(new VectorTileLayer({
   const header = document.createElement('div');
   header.classList.add('d-flex');
 
-  const pageNode = document.createElement('div');
-  pageNode.classList.add('flex-grow-1', 'pe-4');
-  header.appendChild(pageNode);
+  const headerGrabbingArea = document.createElement('div');
+  headerGrabbingArea.classList.add('flex-grow-1', 'grabbing-area', 'pe-2', 'me-2');
+  header.appendChild(headerGrabbingArea);
+
+  headerGrabbingArea.onmousedown = function(event) {
+    if (event.button != 0) {
+      return;
+    }
+    const popoverTip = Popover.getInstance(popup).tip;
+    pageNode.classList.add('grabbing-area-grabbed');
+
+    if (!popoverTip.classList.contains('popover-detached')) {
+      /* detach popover tip */
+      popoverTip.classList.add('popover-detached');
+      const rect = popoverTip.getBoundingClientRect();
+      const maxHeight = document.getElementById('map').getBoundingClientRect().height - 1 - rect.top -
+        popoverTip.getElementsByClassName('popover-header')[0].getBoundingClientRect().height;
+
+      const style = popoverTip.style;
+      style.display = 'none'; /* avoid reflows between the following assignments */
+      style.position = 'absolute';
+      style.transform = '';
+      style.inset = `${rect.top}px auto auto ${rect.left}px`;
+      style.display = '';
+    }
+
+    let clientX = event.clientX, clientY = event.clientY;
+    document.onmousemove = function(event) {
+      const offsetX = clientX - event.clientX;
+      const offsetY = clientY - event.clientY;
+      clientX = event.clientX;
+      clientY = event.clientY;
+      popoverTip.style.top  = (popoverTip.offsetTop  - offsetY).toString() + 'px';
+      popoverTip.style.left = (popoverTip.offsetLeft - offsetX).toString() + 'px';
+    };
+
+    document.onmouseup = function(event) {
+      if (event.button != 0) {
+        return;
+      }
+      pageNode.classList.remove('grabbing-area-grabbed');
+      document.onmousemove = null;
+      document.onmouseup = null;
+    };
+  };
+
+  const pageNode = document.createElement('h6');
+  headerGrabbingArea.appendChild(pageNode);
 
   const pageNum = document.createElement('span');
   const pageCount = document.createElement('span');
@@ -891,10 +936,10 @@ map.addLayer(new VectorTileLayer({
       return;
     }
 
-    /* unclear how many feature we'll find, render prev/next buttons invisible for now */
-    pageNode.classList.add('invisible');
-    btnPrev.classList.add('invisible', 'disabled');
-    btnNext.classList.add('invisible', 'disabled');
+    /* unclear how many feature we'll find, don't render prev/next buttons for now */
+    pageNode.classList.add('d-none');
+    btnPrev.classList.add('d-none', 'disabled');
+    btnNext.classList.add('d-none', 'disabled');
 
     map.forEachFeatureAtPixel(event.pixel, function(feature, layer) {
       const properties = feature.getProperties();
@@ -955,10 +1000,10 @@ map.addLayer(new VectorTileLayer({
 
       pageCount.innerHTML = features.length.toString();
       if (features.length == 2) {
-        /* there are ≥2 features, make prev/pre buttons visible */
-        btnNext.classList.remove('invisible', 'disabled');
-        btnPrev.classList.remove('invisible');
-        pageNode.classList.remove('invisible');
+        /* there are ≥2 features, render prev/pre buttons */
+        btnNext.classList.remove('d-none', 'disabled');
+        btnPrev.classList.remove('d-none');
+        pageNode.classList.remove('d-none');
       }
 
       if (popover === null || popover.tip === null) {
diff --git a/style.css b/style.css
index 3377f44..4b78cee 100644
--- a/style.css
+++ b/style.css
@@ -348,6 +348,9 @@ html, body {
   padding: 0.1rem 0.3rem;
 }
 
+.popover-header h6 {
+  margin: 0;
+}
 /* inspired from bootstrap's .btn-close */
 .popover-header .popover-button {
   box-sizing: content-box;
@@ -384,3 +387,18 @@ html, body {
 .popover-header .popover-button-close {
   --popover-button-icon: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='%23000'%3e%3cpath transform='scale(1.3332) translate(-2 -2)' d='M2.146 2.854a.5.5 0 1 1 .708-.708L8 7.293l5.146-5.147a.5.5 0 0 1 .708.708L8.707 8l5.147 5.146a.5.5 0 0 1-.708.708L8 8.707l-5.146 5.147a.5.5 0 0 1-.708-.708L7.293 8z'/%3e%3c/svg%3e");
 }
+
+.popover .grabbing-area {
+  cursor: move; /* fallback if grab cursor is unsupported */
+  cursor: grab;
+  cursor: -moz-grab;
+  cursor: -webkit-grab;
+}
+.popover .grabbing-area.grabbing-area-grabbed {
+  cursor: grabbing;
+  cursor: -moz-grabbing;
+  cursor: -webkit-grabbing;
+}
+.popover.popover-detached > .popover-arrow {
+  display: none;
+}
-- 
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