What the Top Line Fill tool does
The Top Line Fill tool in Photoshop lets you fill a selected area or layer with color, pattern, or gradient by dragging a line across your image. Instead of clicking a bucket and watching it flood an area, you draw a single stroke — the tool reads the direction and distance of your line and applies the fill based on that input. It's useful when you want precise control over how a gradient transitions or how a pattern aligns, and it works faster than setting up multiple tool options before filling.
The tool lives in the toolbar on the left side of your screen. If you don't see it when ready, it may be grouped with another fill tool — click and hold on the bucket fill icon to reveal the hidden tools in that group.
Key Takeaways
- The Top Line Fill tool applies color, pattern, or gradient by the direction and length of a single line you draw across your selection.
- You set what to fill with (solid color, pattern, or gradient) in the tool options before you draw the line.
- The line you draw determines the gradient transition or pattern scale, so a longer line spreads the fill over more distance.
- The tool works only on a selection or layer; if nothing is selected, make a selection first or the tool will have no effect.
- Undo with Ctrl+Z (Windows) or Command+Z (Mac) if the fill doesn't look right, then adjust your line and try again.
Setting up the tool before you draw
Open the tool options panel (usually docked on the right side of your screen, or go to Window > Tool Options if it's hidden). At the top, you'll see a dropdown that says "Foreground Color", "Pattern", or "Gradient" — this controls what the tool will fill with when you draw your line.
If you want to fill with a solid color, choose "Foreground Color" and set your foreground color in the color swatches (the two overlapping squares in the toolbar). If you want a pattern, select "Pattern" and pick one from the pattern library below. If you want a gradient, select "Gradient" and choose which gradient from the gradient picker.
Below those options, you'll see settings for opacity, blend mode, and whether to fill the entire selection or just the stroke area. Leave these at their defaults unless you have a specific reason to change them — most of the time you want 100% opacity and Normal blend mode.
Drawing the line and explore the fill
Make sure you have a selection active (Select > All if you want to fill the whole layer, or use the rectangular, elliptical, or free selection tool to select just part of your image). If you're working with a gradient, the direction and length of your line control how the gradient transitions — a short line creates a steep transition, a long line spreads it out.
Click and drag across your selection in the direction you want the fill to go. For a gradient, drag from where you want the color to start to where you want it to end. For a pattern, the line length controls how the pattern scales. Release the mouse button, and the fill applies when ready.
If the result isn't what you wanted, press Ctrl+Z (Windows) or Command+Z (Mac) to undo, then draw a new line. You don't need to change any settings — just draw again.
Using Top Line Fill with gradients
Gradients are where this tool shines. Instead of opening the gradient tool, setting the angle, and adjusting the scale in a separate step, you draw one line and you're done. A diagonal line creates a diagonal gradient transition. A vertical line creates a vertical transition. The longer your line, the more gradual the color shift.
If you have a gradient selected that goes from blue to red, and you draw a short horizontal line, the blue-to-red transition happens over just that short distance. If you draw a long horizontal line across the whole image, the same gradient spreads out and transitions slowly. This makes it straightforward to experiment — draw, undo, draw again with a different line length or angle until it looks right.
Using Top Line Fill with patterns
When you fill with a pattern, the line you draw controls the scale and alignment of the pattern tiles. A short line creates a tight, dense pattern. A long line stretches the pattern out. The direction of your line also affects how the pattern aligns within your selection.
This is most useful when you want a pattern to flow in a specific direction or when you want to control how large the pattern appears without opening the pattern options separately. Draw the line, see the result, and undo if you need to adjust the scale.
Common reasons the tool doesn't work
If you draw a line and nothing happens, the most common cause is that you don't have a selection active. The Top Line Fill tool only works within a selection or on a layer that has a selection. Make a selection first — even Select > All will work — then draw your line.
If the fill appears but looks wrong, check that you have the right fill type selected (Foreground Color, Pattern, or Gradient) and that you're using the color or pattern you intended. If the gradient direction is backwards, undo and draw the line in the opposite direction.
If the tool seems slow or unresponsive, you may have a very large selection or a complex pattern. This is normal — Photoshop is processing the fill across a large area. Wait a moment for it to complete.
When to use Top Line Fill instead of other methods
Use the Top Line Fill tool when you want to fill a selection with a gradient and you want to control the angle and spread in one action. It's faster than the gradient tool for straightforward fills because you don't have to adjust separate options.
Use it with patterns when you want the pattern to scale or align in a specific way without opening the full pattern options. For solid color fills, the bucket fill tool is usually simpler — just click once and you're done. For complex fills or when you need to adjust opacity or blend mode, the regular fill dialog (Edit > Fill) gives you more control.
Frequently Asked Questions
Can I use Top Line Fill on a layer without a selection?
No. The tool requires an active selection to work. If you want to fill the entire layer, go to Select > All first, then draw your line. The selection will be removed after you fill.
What's the difference between Top Line Fill and the regular gradient tool?
The gradient tool lets you adjust the angle, scale, and other options in the tool options panel, then drag to explore. Top Line Fill does it all in one drag — the line you draw sets the angle and scale at the same time. Top Line Fill is faster for straightforward gradients; the gradient tool gives more control for complex ones.
Can I fill with a custom color I just mixed?
Yes. Set your foreground color to the color you want, then choose "Foreground Color" in the Top Line Fill tool options. Draw your line and the fill will use that color.
Why does my pattern look stretched or distorted?
The line you draw controls the pattern scale. A very long line stretches the pattern across a large distance, which can make it look distorted. Try drawing a shorter line, or undo and adjust the pattern scale in the tool options before drawing again.
Can I fill multiple selections at once with Top Line Fill?
No. The tool fills one selection per line. If you have multiple selections, you'll need to draw a line for each one, or combine them into a single selection first using Select > Combine.