1 files changed, 60 insertions, 0 deletions
diff --git a/src/background/usecases/ZoomPresenter.ts b/src/background/usecases/ZoomPresenter.ts
new file mode 100644
index 0000000..5a3c64d
--- /dev/null
+++ b/src/background/usecases/ZoomPresenter.ts
@@ -0,0 +1,60 @@
+const ZOOM_SETTINGS = [
+  0.33,
+  0.5,
+  0.66,
+  0.75,
+  0.8,
+  0.9,
+  1.0,
+  1.1,
+  1.25,
+  1.5,
+  1.75,
+  2.0,
+  2.5,
+  3.0,
+] as const;
+
+export default interface ZoomPresenter {
+  zoomIn(): Promise<void>;
+  zoomOut(): Promise<void>;
+  resetZoom(): Promise<void>;
+}
+
+export class ZoomPresenterImpl implements ZoomPresenter {
+  async zoomIn(): Promise<void> {
+    const tab = await browser.tabs.query({
+      active: true,
+      currentWindow: true,
+    });
+    const tabId = tab[0].id as number;
+    const current = await browser.tabs.getZoom(tabId);
+    const factor = ZOOM_SETTINGS.find((f) => f > current);
+    if (factor) {
+      return browser.tabs.setZoom(tabId, factor);
+    }
+  }
+
+  async zoomOut(): Promise<void> {
+    const tab = await browser.tabs.query({
+      active: true,
+      currentWindow: true,
+    });
+    const tabId = tab[0].id as number;
+    const current = await browser.tabs.getZoom(tabId);
+    const factor = ZOOM_SETTINGS.slice(0)
+      .reverse()
+      .find((f) => f < current);
+    if (factor) {
+      return browser.tabs.setZoom(tabId, factor);
+    }
+  }
+
+  async resetZoom(): Promise<void> {
+    const tab = await browser.tabs.query({
+      active: true,
+      currentWindow: true,
+    });
+    return browser.tabs.setZoom(tab[0].id, 1);
+  }
+}