web/_posts/2019-08-08-write-a-new-post.md
Cotes Chung d5413a954f Update posts
- Set width and height for images
- Update the related tutorial
2021-07-03 05:11:11 +08:00

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---
title: Writing a New Post
author: Cotes Chung
date: 2019-08-08 14:10:00 +0800
categories: [Blogging, Tutorial]
tags: [writing]
---
## Naming and Path
Create a new file named `YYYY-MM-DD-TITLE.EXTENSION` and put it in the `_posts/` of the root directory. Please note that the `EXTENSION` must be one of `md` and `markdown`.
## Front Matter
Basically, you need to fill the [Front Matter](https://jekyllrb.com/docs/front-matter/) as below at the top of the post:
```yaml
---
title: TITLE
date: YYYY-MM-DD HH:MM:SS +/-TTTT
categories: [TOP_CATEGORIE, SUB_CATEGORIE]
tags: [TAG] # TAG names should always be lowercase
---
```
> **Note**: The posts' ***layout*** has been set to `post` by default, so there is no need to add the variable ***layout*** in Front Matter block.
### Timezone of date
In order to accurately record the release date of a post, you should not only setup the `timezone` of `_config.yml` but also provide the the post's timezone in field `date` of its Front Matter block. Format: `+/-TTTT`, e.g. `+0800`.
### Categories and Tags
The `categories` of each post is designed to contain up to two elements, and the number of elements in `tags` can be zero to infinity. For instance:
```yaml
categories: [Animal, Insect]
tags: [bee]
```
## Table of Contents
By default, the **T**able **o**f **C**ontents (TOC) is displayed on the right panel of the post. If you want to turn it off globally, go to `_config.yml` and set the value of variable `toc` to `false`. If you want to turn off TOC for specific post, add the following to post's [Front Matter](https://jekyllrb.com/docs/front-matter/):
```yaml
---
toc: false
---
```
## Comments
Similar to TOC, the [Disqus](https://disqus.com/) comments is loaded by default in each post, and the global switch is defined by variable `comments` in file `_config.yml` . If you want to close the comment for specific post, add the following to the **Front Matter** of the post:
```yaml
---
comments: false
---
```
## Mathematics
For website performance reasons, the mathematical feature won't be loaded by default. But it can be enabled by:
```yaml
---
math: true
---
```
## Mermaid
[**Mermaid**](https://github.com/mermaid-js/mermaid) is a great diagrams generation tool. To enable it on your post, add the following to the YAML block:
```yml
---
mermaid: true
---
```
Then you can use it like other markdown language: surround the graph code with ```` ```mermaid ```` and ```` ``` ````.
## Images
### Preview image
If you want to add an image to the top of the post contents, specify the attribute `src`, `width`, `height` and `alt` for the image:
```yaml
---
image:
src: /path/to/image/file
width: 1000 # in pixels
height: 400 # in pixels
alt: image alternative text
---
```
Except for `alt`, all other options are necessary, especially the `width` and `height`, which are related to user experience and web page loading performance. Later section ["Image size"](#image-size) will also mention this.
### Image caption
Add italics to the next line of an imagethen it will become the caption and appear at the bottom of the image:
```markdown
![img-description](/path/to/image)
_Image Caption_
```
### Image size
In order to prevent the page content layout from shifting when the image is loaded, we should set the width and height for each image:
```markdown
![Desktop View](/assets/img/sample/mockup.png){: width="700" height="400" }
```
### Image position
By default, the image is centered, but you can specify the position by using one of class `normal` , `left` and `right`. For example:
- **Normal position**
Image will be left aligned in below sample:
```markdown
![Desktop View](/assets/img/sample/mockup.png){: .normal }
```
- **Float to the left**
```markdown
![Desktop View](/assets/img/sample/mockup.png){: .left }
```
- **Float to the right**
```markdown
![Desktop View](/assets/img/sample/mockup.png){: .right }
```
> **Limitation**: Once you specify the position of an image, it is forbidden to add the image caption.
### Image shadow
The screenshots of the program window can be considered to show the shadow effect, and the shadow will be visible in the `light` mode:
```markdown
![Desktop View](/assets/img/sample/mockup.png){: .shadow }
```
### CDN URL
If you host the images on the CDN, you can save the time of repeatedly writing the CDN url by assigning the variable `img_cdn` of `_config.yml` file:
```yaml
img_cdn: https://cdn.com
```
Once `img_cdn` is assigned, the CDN url will be added to the path of all images (images of site avatar and posts) starting with `/`.
For instance, when using images:
```markdown
![The flower](/path/to/flower.png)
```
The parsing result will automatically add the CDN prefix `https://cdn.com` before the image path:
```html
<img src="https://cdn.com/path/to/flower.png" alt="The flower">
```
## Pinned Posts
You can pin one or more posts to the top of the home page, and the fixed posts are sorted in reverse order according to their release date. Enable by:
```yaml
---
pin: true
---
```
## Code Block
Markdown symbols ```` ``` ```` can easily create a code block as following examples.
```
This is a common code snippet, without syntax highlight and line number.
```
## Specific Language
Using ```` ```language ```` you will get code snippets with line numbers and syntax highlight.
> **Note**: The Jekyll style `{% raw %}{%{% endraw %} highlight LANGUAGE {% raw %}%}{% endraw %}` or `{% raw %}{%{% endraw %} highlight LANGUAGE linenos {% raw %}%}{% endraw %}` are not allowed to be used in this theme !
```yaml
# Yaml code snippet
items:
- part_no: A4786
descrip: Water Bucket (Filled)
price: 1.47
quantity: 4
```
### Liquid Codes
If you want to display the **Liquid** snippet, surround the liquid code with `{% raw %}{%{% endraw %} raw {%raw%}%}{%endraw%}` and `{% raw %}{%{% endraw %} endraw {%raw%}%}{%endraw%}` .
{% raw %}
```liquid
{% if product.title contains 'Pack' %}
This product's title contains the word Pack.
{% endif %}
```
{% endraw %}
## Learn More
For more knowledge about Jekyll posts, visit the [Jekyll Docs: Posts](https://jekyllrb.com/docs/posts/).