Fixed line spacing and first line of a page

[gulliver1]

Hi,
I’m using Writer (LibreOffice 24.8.5) on Windows 10.

I have noticed that the first line of every page does not respect the vertical space specified in the fixed line spacing and instead uses a vertical space that depends on the font and font size.

I have searched this forum and found another user reporting this behavior:

@ajlittoz

Regarding line spacing, this parameter is managed in a subtle way. It is used of course to space lines apart, also to decide where to break pages. However, when you start a new page, the base line is set at a distance equal the glyph size as reported by the font. No extra spacing is added above the glyphs.

To convince yourself, write a demo file in 36 pt with double line spacing. You’ll notice that every first line is flushed at top of page. The spacing you think there is depends on the actual characters you have because they all are designed with various heighs but thay all align on the base line.

When I set line spacing to fixed, my expectation is that every line in the paragraph will be vertically spaced as specified, including the first line of the page.

In the following example I have set a display grid to show you where each line should land. The grid rows are spaced 12pt, starting from the page top margin. The paragraph style has a fixed line spacing of 12pt. As you can see, the first line is vertically spaced from the page top margin less than 12pt, while the other lines/paragraphs are using the correct vertical line spacing.

To show you that the issue is only in the first line of the page, I have created a paragraph style that uses above paragraph spacing to correct the vertical line spacing of the first line of the page. As you can see, every line now matches the grid.

Note that this paragraph style is a workaround and not the solution for controlling vertical line spacing. As you can see in the image below, as soon as a long paragraph breaks into a new page, the first line of the new page uses again less than 12pt from the page top margin.

Note that I’m aware of the page line-spacing (register-true) feature, but finding a method to align every line to a grid is not my point. I chose the above example because it was the simplest way I could think of to illustrate the issue. I’m not interested in aligning every line to a grid. I’m interested in having control of vertical line spacing.

Now to the questions:

Is there a specific reason why the first line of each page doesn’t follow the vertical line spacing specified in fixed line spacing? If this is unintended behavior, what’s the proper channel to suggest a change or report this as a bug?"

[ajlittoz]

Please edit your question to elaborate more on the expected result. Describe the spacing above and below the paragraph. Tell which line spacing you want to define. What is your expectation at top of page?

The various options in the dialog correspond to different computing modes (which parameter is modified in the font metrics). So, for the time being, don’t focus on this choice; explain the typographical look you want to achieve.

As usual, don’t omit OS name, LO version and save format.

[gulliver1]

As you suggested, I have tried to improve the post. Please let me know if my point is more clear now.

[ajlittoz]

Creating a “contextual style” is usually a bad idea, akin to direct formatting. It will play dirty tricks on your back sooner or later.

In your case, this is the special paragraph style for the first paragraph in the page. When you edit your text, the “first” paragraph will not necessarily remain the same.

What I don’t understand is the rationale to lock the base line to some grid. Have you any publishing constraint, like printing on specific stationery with pre-printed lines and you need precise alignment?

Regarding the various spacing options, here are my observations (as a user, not a developer):

• Proportional: seems to apply a magnifying factor to the whole line height in the font metrics
• Leading: leaves glyph height unchanged but replaces separating space between lines
• Fixed: replaces the full height (glyph+leading)

They override line height given by the font metrics. What you did not take into account is that line height is not counted from baseline. Line height is very schematically the sum of ascent, x-height and descent for the glyph proper plus leading between line. Origin of heights is at baseline. That is, you are offset relative to the start of usable area. Also, leading is used only between lines, not on first line.

You also have a confusion between paragraph and character levels. Font metrics defines a bounding box for a glyph (with leading separating bounding boxes in successive lines). These glyph boxes are rendered inside the paragraph bounding box. Spacing is added above and below according to paragraph style. Spacing above offsets the bounding box downwards, but this happens only at start of paragraph. If your paragraph spans a page limit, spacing above will not be added because the break occurred in the middle of the paragraph.

The only way I know to align lines on a grid is registering (now labelled "page spacing in “recent” Writer releases). It requires two settings to work as expected.

• page style: the feature must be enabled in the page style(s) and a paragraph style is set as a reference to define the grid
• paragraph style(s): registering, aka page-spacing, is enabled in every paragraph style to align on the grid

Registering has a “quantizing effect”: paragraph line height is forced to grid distance and spacing between paragraphs is rounded above to the nearest quantum. So, exercise caution when constraining several paragraph styles: their effective lineheight and spacing will be slightly different from what is shown in the dialog.

You can also mix registered and non-registered text/styles in a page but this’ll probably result in a clumsy look with erratic spacing at transitions.

[gulliver1]

Hi ajlittoz,
thank you for the detailed reply.

@ajlittoz

Creating a “contextual style” is usually a bad idea, akin to direct formatting. It will play dirty tricks on your back sooner or later.

In your case, this is the special paragraph style for the first paragraph in the page. When you edit your text, the “first” paragraph will not necessarily remain the same.

I agree that creating a paragraph style specifically for the first line of the page is a bad idea. I edited again the first post to make more clear why in my example I created it.

@ajlittoz

What I don’t understand is the rationale to lock the base line to some grid. Have you any publishing constraint, like printing on specific stationery with pre-printed lines and you need precise alignment?

I chose the example because it was the simplest way I could think of to illustrate the issue. I’m not interested in aligning every line to a grid. I’m interested in having control of vertical line spacing.

@ajlittoz

Regarding the various spacing options, here are my observations (as a user, not a developer):

• Proportional: seems to apply a magnifying factor to the whole line height in the font metrics
• Leading: leaves glyph height unchanged but replaces separating space between lines
• Fixed: replaces the full height (glyph+leading)

They override line height given by the font metrics. What you did not take into account is that line height is not counted from baseline. Line height is very schematically the sum of ascent, x-height and descent for the glyph proper plus leading between line. Origin of heights is at baseline. That is, you are offset relative to the start of usable area. Also, leading is used only between lines, not on first line.

I think your observations make sense. The way I see it, Fixed is the only option users have for manually controlling line spacing. The other options set the line spacing automatically based on what the font specifies or semi-automatically by mixing what the font specifies with a user-defined value. My issue with the current implementation is that Fixed gives manual control of line spacing for every line, except the first line of the page!

@ajlittoz

You also have a confusion between paragraph and character levels. Font metrics defines a bounding box for a glyph (with leading separating bounding boxes in successive lines). These glyph boxes are rendered inside the paragraph bounding box. Spacing is added above and below according to paragraph style. Spacing above offsets the bounding box downwards, but this happens only at start of paragraph. If your paragraph spans a page limit, spacing above will not be added because the break occurred in the middle of the paragraph.

I understand, that’s one of the reasons why the paragraph style specific for the first line of the page is not a solution to the issue.

@ajlittoz

The only way I know to align lines on a grid is registering (now labelled "page spacing in “recent” Writer releases). It requires two settings to work as expected.

• page style: the feature must be enabled in the page style(s) and a paragraph style is set as a reference to define the grid
• paragraph style(s): registering, aka page-spacing, is enabled in every paragraph style to align on the grid

Registering has a “quantizing effect”: paragraph line height is forced to grid distance and spacing between paragraphs is rounded above to the nearest quantum. So, exercise caution when constraining several paragraph styles: their effective lineheight and spacing will be slightly different from what is shown in the dialog.

You can also mix registered and non-registered text/styles in a page but this’ll probably result in a clumsy look with erratic spacing at transitions.

Yes, this can be a solution to the specific case of someone who needs to align lines on a grid, but it’s not a solution to someone who needs to control vertical line spacing of every line.

[ajlittoz]

Please be more specific about why you want to control vertical spacing of “every” line. For me, it is enough that lines be spaced uniformly or as I requested them.

The only case where you get irregular spacing is when you mix several sizes in a line. Then line height may be different on successive lines and it may de desirable for aesthetic reasons to force a common spacing in the paragraph.

I still don’t understand why you focus on the position of the first baseline in the page. It will always be determined by font metrics eventually marginally modified by paragraph style settings. IMHO, it is important when you have multi-column text. But any heading or different paragraph style will likely cancel cross-column alignment unless you activated registering.

Since the first contents line is set below the header or the margin and is thus preceded by white space, the average reader can’t tell if the line is exactly on your “grid” or not. The difference is infinitesimal

So, tell exactly what you are looking for (some kind of objective specification) so that I can give an appropriate advice.

[gulliver1]

@ajlittoz

Please be more specific about why you want to control vertical spacing of “every” line.

@ajlittoz

I still don’t understand why you focus on the position of the first baseline in the page.

I want to control vertical positioning of every line because I want to precisely reproduce any design. In order to control vertical positioning I have the following options:

• Spacing: Above paragraph
• Spacing: Below paragraph
• Spacing: Do not add space between paragraphs of the same style
• Line Spacing: Fixed
• Line Spacing: Activate page line-spacing

So far I have only talked about “line spacing” because all the above options work great, except Line Spacing: Fixed, which vertically shifts the design starting from the first line of every page/column. The amount of this shift is calculated using a value stored inside the font file. This is a problem because the amount of this value:

• is unknown to the user (unless you guess it by eye or inspect the font file with a specialized program)
• typically changes when you change font size
• typically changes when you change font

I think that, when the user specify Line Spacing: Fixed, the calculation for the vertical position of the first line of the page should use the specified fixed value instead of the value stored inside the font file. I still don’t understand why it’s implemented in the current way. I’ll see if I can attach this thread to a bug report or feature request.

@ajlittoz

So, tell exactly what you are looking for (some kind of objective specification) so that I can give an appropriate advice.

I appreciate that you want to help me. Let me think about whether it is worth your time (and mine) to discuss how to solve a specific example, when this issue is not really about a specific example.

[LeroyG]

Test with the character superscript position: