So, let's continue to dissect these nice presentation templates from our Indonesian community. Download the same template as in previous article. Open it in LibreOffice Impress and look at first slide:
Try click somewhere on slide in area with rectangles. You can select any from these rectangles include the largest grey rectangle that author used as background for all composition. Its all are just shapes! This is an absolutely wrong way when you create a presentation template!
First, user shouldn't have an opportunity to select any slide background elements. This will interfere with and distract him from creating the presentation. User should understand clear that he can change only heading text on first slide of his future presentation.
And second problem with these many shapes is its size. Every shape is an different object with own parameters, like position on page/slide, z-order, weight and height, area color/gradient, etc. and therefore every shape has a not small size.
The best way here is to create a background for your slide in another graphic software, like LibreOffice Draw in our case (or GIMP or Inkscape). Note, your image should have the same size as your future presentation template, like 16:9 or 4:3, or A4. Then save that image as PNG with the best quality somewhere on your PC.
A next step is to set up your image as background for a slide. There are several methods for it. Simpliest method is follow: open a Properties section in Sidebar. Press a "Insert image" button. Find and select your image in "Set background image" dialog and press "Open" button there. Voila! You have a slide background (I used another image and I before deleted all these shapes just for visibility):
And user can select and change only text on the slide.
Note, that LibreOffice logo in bottom left corner is a different object too. But in this case it's an image and user still can select it even after our background changing. But logo on the slides is another story with another method of the work with Impress.
This is not completely true, though. Yes, in a vector format like ODP, each shape is represented as an individual object with different parameters, and these take up space. Usually, however, a vector graphic ends up being much smaller than the same graphic rendered in a bitmap format like PNG. Since I couldn't download the presentation you linked (server seems to be inaccessible), I created my own presentation that consists of one slide with 72 rectangles in five different colors. The ODP file is 13 KB in size, a PNG at a resolution of 647 × 345 takes up 16 KB - and this example is very favorable towards the PNG format: Shapes with uniform colors compress well, and shapes with straight horizontal and vertical lines will show almost no scaling artifacts. Try saving a bunch of gradient-filled circles as PNG and you will see a drastic increase in file size (22 KB ODP vs. 200 KB PNG in my experiments) and a noticeably lower visual quality.
ReplyDeleteIf the user should not be able to directly modify graphical elements of a presentation, my recommendation is to put them on a master slide. You can create different masters for the title and regular slides.
I know about master slide. It was an idea for next my article. My main idea in this article was to show another way for background creating.
DeleteThanks for your comment anyway, your experiment with vector/PNG comparizon is interesting.